The IMRD structure with its constituents Introduction, Method, Results and Discussion is acknowledged as the norm for writing abstracts by most. Researchers need to adhere to the norm in order for their abstracts to function as effective advertisements for their research articles, and students need to comply with the norm should they want their abstracts to serve as connectors to the academic world. The aim of this thesis is to examine to what extent abstracts written in English by Swedish students adhere to the IMRD norm. A total of 40 bachelor’s thesis abstracts in English linguistics and physics were analyzed in terms of macro structure, the inclusion, exclusion and order of the constituent parts, and micro structure, the linguistic realization of the constituents. The results show that the English linguistics and physics abstracts fail to meet the requirements of the IMRD norm on several points. This suggests that the students are either unaware of the important function fulfilled by abstracts or need more guidance and practice. The conclusions are necessarily tentative since further research is required to provide a comprehensive picture, but still, the results suggest that Swedish students’ abstract writing needs to be given higher priority.

Cette thèse est consacrée à l'étude de la formation des prix sur les marchés financiers, en particulier lorsque ceux-ci se composent d'un grand nombre d'agents. On commence par l'étude empirique d'un marché émergent -- le bitcoin -- de manière à mieux comprendre comment les actions individuelles affectent les prix -- ce que l'on appelle « l'impact de marché ». On développe ensuite un modèle théorique d'impact basé sur le concept d'agent hétérogène, qui parvient à reproduire les observations empiriques d'un impact concave dans un marché non manipulable. Le cadre de l'agent hétérogène nous permet de revisiter les concepts d'offre et de demande dans un cadre dynamique, de mieux comprendre l'impact du mécanisme de marché sur la liquidité, ou encore de poser les bases d'un simulateur de marché réaliste. On montre enfin, à travers l'étude empirique de plusieurs bulles et crashs sur le marché du bitcoin, le rôle crucial de la micro-structure dans la compréhension des phénomènes extrêmes. / This thesis is devoted to the study of price formation on financial markets, in particular when these are composed of a large number of agents. We start by the empirical study of an emergent market -- the bitcoin -- in order to better understand how individual actions impact prices -- a phenomenon known as « market impact ». We then develop a theoretical model based on the concept of heterogeneous agents, that allows to reproduce the empirical observations of a concave impact in a market that remains non-manipulable. The heterogeneous agents framework allows us to revisit the concepts of supply and demand in a dynamic context, to better understand how the choice of a particular market mechanism can impact liquidity, and to lay some grounds for a realistic market simulator. By studying several bubbles and crashes that happened on the bitcoin market, we finally show how relevant microstructure effects can be, in particular for understanding the occurrence of extreme phenomena.

We consider Sequential Monte Carlo Approximate Bayesian Computation (SMC ABC) as a method of calibration for the use of agent based models in market micro-structure. To date, there are no successful calibrations of agent based models to high frequency trading data. Here we test whether a more sophisticated calibration technique, SMC ABC, will achieve this feat on one of the leading agent based models in high frequency trading literature (the Preis-Golke-Paul-Schneider Agent Based Model (Preis et al., 2006)). We find that, although SMC ABC's naive approach of updating distributions can successfully calibrate simple toy models, such as autoregressive moving average models, it fails to calibrate this agent based model for high frequency trading. This may be for two key reasons, either the parameters of the model are not uniquely identifiable given the model output or the SMC ABC rejection mechanism results in information loss rendering parameters unidentifiable given insucient summary statistics.

No description available.

Yes / This paper investigates the strength and ductility of concrete confined by Glass/Epoxy ±55° Filament Wound Pipes (GFRP) under axial compression. A total of 24 cylinderical specimens were prepared with expansive and Portland cements, properly compacted and un-compacted for different composite fresh concrete matrix. Test results showed that compressive strength and axial deformation at failure of concrete confined with GFRP tubes increased by an average of 2.85 and 5.57 times these of unconfined concrete, respectively. Macro and micro analyses of GFRP pipes after failure were also investigated. Debonding, whitening, matrix/transfer cracking, delamination and splitting mechanisms were detected at failure, respectively. The experimental results were also employed to assess the reliability of design models available in the literature for confined concrete compressive strength.

<p>The appearance and design of a package are key properties to attract and to focus the attention of a customer. Print quality contributes to a great degree to achieve these requirements. Most critical perceived in terms of quality are print defects like mottling, gloss and stripiness, which all appear in the printing of corrugated board. Stripiness is especially critical because it is a defect directly caused by the corrugated board construction. A further cause can be generated by the production process of corrugated board. Pre-studies by Odeberg Glasenapp (2004) revealed a difference in surface micro-roughness between the regions on the peak line of the liner and the regions in the valley between two peaks of the corrugation. This knowledge was the basis for the work described in this thesis.</p><p>In a first stage, laboratory trials were conducted with sets of coated and uncoated samples of various grammages. The trial was set-up in order to simulate the conditions in the corrugator as closely as possible. In the evaluations, it was found out that the settings were too high. For that reason, the coated samples were influenced to a too high degree and needed to be excluded from further evaluations. With the uncoated samples, on the other hand, a change in micro surface roughness was detectable. The roughness is decreased on the peaks and the gloss appearance was the conclusion. The analysis of the printed samples focused on shifts in colour and print density. It is unclear if both are affected only surface roughness changes and/or by the typical corrugated board effect of washboarding.</p><p>A full-scale test was performed in order to confirm the results of the laboratory test. A test series was chosen with coated and uncoated outer liners. Contrary to the lab-test results, the uncoated grades showed no surface roughness changes. Instead, the coated samples were affected to a great extent. The changes in surface roughness and gloss appearance were similar to the lab-test. This confirms that the lab-test samples were exposed to heat, pressure and shear to a too high degree. The print analysis of the full-scale test did not agree with the laboratory test. Gloss lines were visually detectable, but they were difficult to measure. A reason could be that the ink is capable on forming an ink film layer on top of the surface of the paper. This would cover the micro roughness of the matt parts thereby creating an almost homogeneous glossy appearance.</p>

In this thesis different mechanical properties for shotcrete (sprayed concrete) such as compression strength, bond strength, bending tensile strength, elastic modulus, free and restrained shrinkage as a function of its age was investigated. One of the main issues was to investigate the difference between ordinary cast concrete and shotcrete. Reliable material data for young and hardening shotcrete is scarce which in the past have made such comparisons difficult. Also, less accurate data representative for cast concrete has often been used in numerical modelling and design analyses. The focus of the project has particularly been on the properties bond strength and restrained shrinkage for which two new testing methods has been developed and evaluated. Microstructural studies have also been performed as a complement to the bond strength testing. The bond to rock is one of the most important properties for shotcrete used as rock reinforcement. During the very first time after spraying the physical properties and the bond to the rock depend on the set accelerator and the micro structure that is formed. The investigation of early age bond strength of shotcrete is of great importance both from a production perspective and a safety perspective. The newly developed method was tested and evaluated and proved that it can be used for bond strength testing already from a couple of hours after shotcreting. The bond, or adhesion, depends on several factors such as texture of the rock, the type of accelerator, application technique, etc. In this work the development of the microstructure in the interfacial transition zone (ITZ) and strength of the bond was investigated. The results show that the bond strength is related to the hydration process, i.e. the strength gain of the shotcrete. The early development of the ITZ was here studied using a scanning electron microscope (SEM) making it possible to observe changes over time, before and after proper cement hydration. Restrained shrinkage cracking of shotcrete, especially in the case of shotcrete sprayed on soft drains that are parts of a tunnel lining not continuously bonded to the rock, can be detrimental for the sustainability of an infrastructure tunnel system. Maintenance and repair costs can be high over time. It is shown that the developed test method realistically captures the behaviour of shotcrete drains on hard rock in situ. The method can be used in the evaluation of different technical solutions for avoiding or minimizing shrinkage cracks in shotcreted soft drains. It can also be used to assess the performance of shotcrete fully bonded to a rock surface, with respect to the ability to prevent cracking or to distribute possible shrinkage damage into several fine cracks instead of one wide. / <p>QC 20140526</p>

There are many variables that affect the viscoelastic properties of asphalt mixtures with time, among which age hardening may be considered one of the important ones. Age hardening of asphalt mixtures is an irreversible process, which contributes to a reduction of the durability of pavements and eventually increases the maintenance cost. Beside the environmental effects, ageing in asphalt mixture depends on the physicochemical properties of bitumen and mixture morphology which is a combined effect of aggregate packing, porosity, air void distribution and their interconnectivity. Thus, a clear understanding on the physicochemical properties of bitumen and mixture morphology may help to predict the performance of asphalt mixtures, which will contribute to longer-lasting and better performing pavements. When looking at the bitumen at micro-scale, one can see microstructures appearing under certain conditions which can be partially explained by the interaction of the individual phases. Since the thermo-rheological behavior of bitumen depends largely on its chemical structure and intermolecular microstructures, studying these can lead to understanding of the mechanism, speed and conditions under which this phase behavior occurs. Linking this to the changes in properties of bitumen can thus lead to better understanding of the causes of ageing, its dominant parameters and the resulting diminished mechanical response. To investigate ageing in asphalt pavements, along with physicochemical properties of bitumen one needs to also focus on the influence of mixture morphology.  It is known that asphalt mixtures with similar percentages of air-voids can have different morphologies and thus can age differently. Prediction of ageing behavior without considering the influence of mixture morphology may thus lead to erroneous conclusions and non-optimal mix design. Hence, it is important to understand the interplay between the mixture morphology and ageing susceptibility and relate this to the long term mixture performance. The aim of this Thesis was to develop fundamental understanding on ageing in asphalt mixtures that can contribute to the asphalt community moving away from the currently used accelerated ageing laboratory tests and empirical models that can lead to erroneous conclusions. To reach this aim, experimental and numerical micro-scale analyses on bitumen and meso-scale investigations on mixture morphology have been performed which, collectively, allowed for the development of a method for the prediction of asphalt field ageing, incorporating both mixture morphology and micro-scale bitumen mechanisms. For this, first, the mechanisms of surface ageing and diffusion controlled oxidative ageing were identified. Secondly, the influence of mixture morphology on asphalt ageing susceptibility was investigated. Procedures to determine the controlling parameter were then developed and an empirical framework to quantify the long-term field ageing of asphalt mixtures was set-up. For this, a combination of experimental and numerical methods was employed. An extensive experimental study was carried out to understand the fundamental mechanisms behind the micro-structural phase appearance and the speed or mobility at which they change. Atomic Force Microscopy (AFM) was utilized at different temperatures to investigate the phase separation behavior for four different types of bitumen and co-relate it with the Differential Scanning Calorimetry (DSC) measurements. Based on the experimental findings, it was concluded that the observed phase separation is mainly due to the wax/paraffin fraction presence in bitumen (Paper I). A hypothesis was developed of the appearance of a thin film at the specimen surface due to ageing which is creating a barrier, restricting thus the microstructures to float towards the surface. Furthermore, investigation showed that depending on the bitumen and exposure types this surface thin film is water soluble and thus the moisture damage becomes more severe with the ageing of asphalt pavement (Paper II and IV). A new empirical relation to obtain the primary structure coating thickness was established utilizing mixture volumetric properties and gradation using a large set of data from different literature sources. It was found that the enhanced morphological framework can be used to optimize the long term performance of asphalt mixtures (Paper III).  Thereafter, the effect of diffusion controlled oxidative ageing on different mixture morphologies based on oxidative ageing mechanism of bitumen and diffusion-reaction process was investigated using the Finite Element Method (FEM). From the FE analyses, the effect of air-void distribution and their interconnectivity combined with the aggregate packing was shown to have a significant effect on age hardening (Paper IV). It was shown that focusing only on the percentage of air-void as the main predictive ageing parameter may lead to an erroneous conclusion and non-optimal predictions of long-term behavior.  To replace such approaches, a new way to predict the long-term ageing was proposed in this Thesis, utilizing the found influences of mixture morphology and fundamental mechanism. Though additional mechanisms and non-linear coupling between them may be still needed to reach the ‘ultimate’ ageing prediction model, the current model was found to be a significant improvement to the currently used methods and may lead the way towards further enhancing the fundamental knowledge towards asphalt mixture ageing (Paper V). / <p>QC 20140509</p>

La matière grasse laitière anhydre (MGLA) est composée à plus de 98 % de triglycérides. Leur diversité, liée à la nature des acides gras estérifiés, induit un comportement complexe de la MGLA lors de sa cristallisation. Par ailleurs, d’autres composés, dits mineurs, présents de manière endogène ou formés lors de procédés de transformation peuvent moduler le processus de cristallisation. Néanmoins, leurs modes d’action sont encore mal connus, rendant la maitrise du processus de cristallisation délicat. La mise en oeuvre de méthodes de caractérisation à différentes échelles (RMN, diffraction des rayons X, microscopie optique, analyse thermique différentielle, rhéologie) et à différentes températures permet de discriminer les mécanismes d’action des composés mineurs sur la cristallisation de la MGLA en phase continue ou dispersée. Ainsi, les composés mineurs modifient la cinétique de cristallisation de la MGLA, en agissant sur ses deux étapes, la nucléation et la croissance. En accélérant ou en ralentissant la vitesse de cristallisation, ils modifient la nature et/ou la structure du réseau cristallin et, éventuellement, les propriétés macroscopiques de la matière grasse. Les mécanismes d’action des composés mineurs sur la cristallisation de la MGLA dépendent de leur nature chimique (longueur de la chaine carbonée, degré d’insaturation, estérification) et de leur concentration. Lorsque la matière grasse est émulsionnée, son confinement et la création d’interfaces complexifient le processus de cristallisation : les composés mineurs modulent la cristallisation via l’interface ou la phase grasse selon leur affinité préférentielle pour l’une ou l’autre des deux phases de l’émulsion et induisent des propriétés thermiques et structurales spécifiques. Ce travail permet, donc, de mieux comprendre les facteurs qui modulent la cristallisation de la matière grasse et ainsi de mieux maitriser l’un des processus déterminants dans l’élaboration de la structure et de la fonctionnalité des produits laitiers. / Anhydrous Milk Fat (AMF) comprises more than 98% triglycerides. The diversity of the esterified fatty acids induces a complex behavior of AMF during crystallization. In addition, other minor components, either endogenously present or added upon processing modulate AMF crystallization. Nevertheless, the mechanisms underlying their mode of action are still poorly understood, making the mastery of fat crystallization difficult. Several characterization methods (NMR, X-ray diffraction, optical microscopy, differential scanning calorimetry, rheology) were implemented to screen a large set of minor components at different scales and temperatures. The approach enabled to gain knowledge about the involved mechanisms, both in bulk and in the emulsified state. Minor components modify the kinetics of AMF crystallization through their impact on the two main stages of the process, nucleation and growth. By accelerating or slowing down the rate of crystallization, they modify the nature and/or the structure of the crystal lattice and, possibly, the macroscopic properties of AMF. The impact of minor components on AMF crystallization depend on their chemical nature (length of the carbon chain, degree of unsaturation, esterification) and on their concentration. When fat is emulsified, confinement and interfacial effects come into play. Minor components modulate crystallization via the oil/water interface or via the fat phase depending on their preferential solubility, which may induce specific thermal and structural properties. On the whole, this study enables a better understanding of the factors that modulate milk fat crystallization and provides useful guidances for a better control of this key process controlling the structure and function of dairy products.

Orientadores: Paulo Roberto Mei, Marcelo Martins / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-10T20:59:53Z (GMT). No. of bitstreams: 1 Ritoni_Marcio_M.pdf: 22898482 bytes, checksum: cebeda09f860c091710fa40d369a641d (MD5) Previous issue date: 2007 / Resumo: O aço inoxidável superaustenítico ASTM A 744 Gr. CN3MN é aplicado na fabricação de equipamentos que trabalham em ambientes sob corrosão severa com solicitação mecânica. Neste trabalho investigou-se a influência dos tratamentos térmicos na microestrutura e propriedades desse tipo de material. Foram realizados tratamentos térmicos de solubilização na faixa de temperaturas entre 1100 e 1250 °C, alívio de tensões entre 500 e 800 °C e tratamentos de envelhecimento a 900 °C, variando-se o tempo em 1,5, 12, 24 e 48 horas. Realizaram-se também ensaios mecânicos (dureza e impacto). As análises microestruturais foram feitas por meio de microscopia ótica, eletrônica de varredura, eletrônica de transmissão e difração de raios-X. Concluiu-se que, para maximizar a resistência ao impacto, a solubilização deve ser feita a 1200 °C, que produz a menor fração volumétrica de precipitados. À medida que a temperatura de alívio de tensões aumenta de 500 para 800 °C, a energia absorvida no impacto reduz-se. Além do aumento na fração volumétrica de precipitados, nas temperaturas acima de 550 °C, observa-se precipitados nos contornos de grãos. Quanto maior a exposição do material à temperatura de 900 °C, menor é a energia absorvida no impacto. Com 1,5 horas a 900 °C o material apresentou redução na resistência ao impacto de 127,7 para 25,0 Joules. A dureza do material apresentou resultado inversamente proporcional à energia absorvida no impacto para todas as temperaturas de tratamento térmico. A amostra bruta de fundição apresentou fase sigma (s) na matriz austenítica. As amostras solubilizadas a 1200 e 1240 °C apresentaram fase sigma (s) e carboneto M6C. O tratamento térmico a 900 °C por 48 horas causou a precipitação de algumas fases na matriz austenítica sendo as mais prováveis: sigma (s), chi (c) e carboneto M23C6 / Abstract: ASTM A 744 Grade CN3MN super-austenitic stainless steel is employed in the manufacture of equipment working in severely corrosive environments under mechanical loads. In this work, an investigation was made of the influence of heat treatments on the microstructure and properties of this type of material. Solution heat treatments were carried out at temperatures ranging from 1100 to 1250 ºC, stress relief between 500 and 800 ºC and aging treatments at 900 ºC, for periods of time varying from 1,5, 12, 24 and 48 hours. Mechanical tests (hardness and impact) were also conducted. The microstructural analyses were carried out by X-ray diffraction, optical microscopy, and by scanning and transmission electron microscopy. It was concluded that, to maximize the material¿s impact strength, the solution heat treatment should be done at 1200 ºC, at which temperature the volumetric fraction of precipitates is lower than at other solution heat treatment temperatures. As the stress relief temperature rose from 500 to 800 ºC, the energy absorbed during impact diminishes. In addition to the increase in the volumetric fraction of precipitates at temperatures above 550 ºC, precipitates were visible at the grain boundaries. The longer the material was exposed to a temperature of 900 ºC the lower the energy absorbed during impact. After 1,5 hours at 900 ºC the material¿s impact strength dropped from 127,7 to 25,0 Joules. The steel¿s hardness was also inversely proportional to the energy absorbed during impact at all the heat treatment temperatures. The as-cast sample presented sigma (s) phase in the austenitic matrix. The samples solution heat treated at 1200 and 1240 ºC presented sigma (s) and M6C carbide phases. The heat treatment at 900 ºC for 48 hours caused precipitation of some phases in the austenitic matrix, the most probable of which were sigma (s), chi (c) and M23C6 carbide / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica