L'une des principales missions de l'Ifremer consiste à étudier les ressources sous-marines et les fonds marins via une flotte océanographique importante, employée à travers le globe. Pour ce faire, les navires sont équipés d'équipements acoustiques de type SONAR afin d'obtenir les informations recherchées dans la colonne d'eau. Dans certaines conditions de navigation, la houle et les mouvements du navire génèrent un entraînement d'air conséquent sous la surface. Des nuages de bulles sont ainsi formés et entraînés sous la carène par l'écoulement. L'interaction entre ces bulles et les ondes acoustiques peuvent entraîner des pertes de données, et par conséquent une diminution importante de la productivité du navire. Les outils permettant l'étude du phénomène sont actuellement limités. Les modèles numériques ne sont pas suffisamment performants, pour simuler conjointement les mécanismes d'entraînement d'air à l'étrave puis l'écoulement dysphasique autour de la carène, et les essais classiques en bassin de traction ne donnent pas entière satisfaction. Dans le cadre de cette thèse, une méthode d'essai spécifique, pour l'étude de ce phénomène, a été développée et mise en place au bassin à houle et courant de l'Ifremer. Cette méthode nécessite la synchronisation entre un générateur de houle et un générateur de mouvement (hexapode), permettant d'imposer les mouvements calculés au préalable par simulation numérique à la maquette. Cette configuration permet d'étudier indépendamment les effets de la houle et des mouvements sur la génération des bulles. L'instrumentation employée permet de filmer et de caractériser l'entraînement d'air à l'étrave de la maquette. Deux mécanismes distincts ont été observés : la génération de bulles par entraînement tourbillonnaire ou par le déferlement de la vague d'étrave. Une méthode de traitement d'image a été élaborée pour analyser ces mécanismes pour de nombreuses configurations d'essais. Une étude paramétrique a été réalisée afin de calculer la fréquence de génération de bulles en fonction de chaque paramètre d'essai. Des mesures PIV de l'écoulement permettent de corréler la dynamique des nuages de bulles et de l'écoulement. L'ensemble des résultats obtenus permet d'apporter des éléments nouveaux pour la compréhension et l'étude du phénomène, avec la perspective d'obtenir un outil fiable facilitant la conception des navires océanographiques. / One of the main assignments of Ifremer is to study the seabed and the resources undersea, through a large oceanographic fleet used across the globe. For that purpose, ships are equipped with different kinds of SONAR (SOund Navigation And Ranging) to obtain the information sought in the water column. In some sea conditions, waves and ship motions generate significant air entrainment below the surface. Bubble clouds are then carried under the hull by the flow. The interaction between these bubbles and the acoustic waves may result in data loss, and therefore in a considerable reduction of the vessel’s productivity. The tools used to study this phenomenon are currently limited : the numerical models are not efficient enough to simulate at a time air entrainment at the bow and the two phase flow around the hull. On the other hand conventional towing tank tests are not entirely satisfactory. During this PhD research work, a specific test method to study this phenomenon has been developed and implemented at the Ifremer wave and current tank. This method requires the synchronization between a wave generator and a movement generator (hexapod) that enables to force the model motions, calculated in advance by numerical simulations. With this configuration, the effects of waves or motions characteristics on the bubbles generation can be studied independently. A complete instrumentation allowed to acquire images sequences to characterize the air entrainment at the bow of the model. Two distinct mechanisms have been observed : the generation of bubbles by vortex shedding or by the breaking bow wave. A post-processing method has been developed to analyse these mechanisms, for many test configurations. A parametric study was performed to calculate the frequency of bubbles generation for each test parameter. PIV measurements allowed to correlate the dynamic of bubbles clouds with the own flow dynamic. The overall results provide new elements for the understanding and the study of the phenomenon, with the final objective of obtaining a reliable tool that facilitates the design of research vessels.

Currently shock effects on surface ships can be determined by full scale shock trials, Finite Element Analysis or semi empirical methods that reduce the analytical problem to a limited number of degrees of freedom and include hull configurations, construction methods and materials in an empirical way to determine any debilitating effects that an explosion may have on the ship. This research has been undertaken to better understand the effect of hull shape on surface ships' shock response to external underwater explosions (UNDEX). The study is within the semi empirical method category of computations. A set of simple closed-form equations has been developed that accurately predicts the magnitude of dynamic excitation of different 2- D rigid-hull shapes subject to far-field UNDEX events. This research was primarily focused on the affects of 2-D rigid hull shapes and their contribution to global ship motions. A section of the thesis,

Il y a peu, j'ai pu lire « qu'on pouvait considérer que les ponts romains de l'Antiquité, pouvaient être considérés comme inefficaces, au regard des standards actuels : ils utilisaient trop de pierre et énormément de travail était nécessaire à leur construction. Au fil des années, pour répondre à une problématique équivalente, nous avons appris à utiliser moins de matériaux et à réduire la charge de travail ». Ces problématiques nous les retrouvons aussi en conception mécanique où l'on essaye en continu de proposer des systèmes de plus en plus performants mais devant être conçus en moins de temps, étant moins cher à produire et fournissant des prestations au moins équivalentes à ce qui a déjà été conçu.Au cours d'un processus de conception classique, les concepteurs définissent une géométrie ne présentant aucun défaut puis, étant donné que les moyens de production ne permettent pas d'obtenir de telles pièces finales, ils spécifient les schémas de cotation définissant les écarts acceptables garantissant le bon fonctionnement du système. Seulement, cela est fait après avoir produit les dessins détaillés, c'est à dire trop tard. Pour répondre à cette problématique, je présenterai l'intégration, très tôt dans le cycle de vie de conception, d'un processus de validation optimisé, basé sur une maquette numérique directement en lien avec sa représentation fonctionnelle (maquette fonctionnelle), et permettant de valider des schémas de cotation 3D standardisés.Je décrirai d'abord ce que l'on entend par « maquette fonctionnelle » et surtout ce que cette nouvelle définition apporte en plus de la définition numérique. Une fois ce point abordé, je détaillerai les liens qui permettent d'avoir une unicité de l'information au sein de l'environnement de travail, tout comme les processus qui permettent de lier les représentations fonctionnelles et numériques.Ensuite, je détaillerai les processus basés sur ces concepts, et qui ont pour but de valider les choix qui sont effectués en avance de phase au niveau des schémas de cotation. Pour ce faire, je commencerai par présenter l'analyse au pire des cas (utilisant les modèles de domaines écarts notamment), permettant de garantir le bon fonctionnement de l'ensemble mécanique, dans le cas ou touts les écarts se retrouvent à l'intérieur des zones respectives (définies par les tolérances).Enfin, je finirai par introduire ce qu'une couche statistique, couplée à l'analyse au pire des cas utilisant les enveloppes convexes, peut amener dans le contexte industriel et notamment sous la contrainte temporelle.

Presburger arithmetic is the first-order theory of the integers with addition and ordering, but without multiplication. This theory is decidable and the sets it defines admit several different representations, including formulas, generators, and finite automata, the latter being the focus of this thesis. Finite-automata representations of Presburger sets work by encoding numbers as words and sets by automata-defined languages. With this representation, set operations are easily computable as automata operations, and minimized deterministic automata are a canonical representation of Presburger sets. However, automata-based representations are somewhat opaque and do not allow all operations to be performed efficiently. An ideal situation would be to be able to move easily between formula-based and automata-based representations but, while building an automaton from a formula is a well understood process, moving the other way is a much more difcult problem that has only attracted attention fairly recently. The main results of this thesis are new algorithms for extracting information about Presburger-definable sets represented by finite automata. More precisely, we present algorithms that take as input a finite-automaton representing a Presburger definable set S and compute in polynomial time the affine hull over Q or over Z of the set S, i.e., the smallest set defined by a conjunction of linear equations (and congruence relations in Z) which includes S. Also, we present an algorithm that takes as input a deterministic finite-automaton representing the integer elements of a polyhedron P and computes a quantifier-free formula corresponding to this set. The algorithms rely on a very detailed analysis of the scheme used for encoding integer vectors and this analysis sheds light on some structural properties of finite-automata representing Presburger definable sets. The algorithms presented have been implemented and the results are encouraging : automata with more than 100000 states are handled in seconds.

ABSTRACT Dr. Alice Hamilton (1869-1970), the leading American figure in industrial medicine during the early to mid-1900s, left behind a body of rhetoric that is important in the history of American feminist discourse and American public address. Her discourse is the exemplary of feminist-pragmatist rhetoric, a genre of cross-gender communication developed by New Women associated with Hull House and the University of Chicago between 1892 and 1918. Hamilton’s rhetoric illuminates a key event in the history of the American rhetorical tradition—the emergence of the modern woman from her late-Victorian beginnings through her Progressive self-transformation. This study is approached as a rhetorical biography. It tracks Hamilton’s evolution from “reticent scientist” to outspoken feminist-pragmatist by examining family, educational, peer and social influences on her development; and through critical analysis of her speeches, technical writing, books, and popular and specialty magazine articles over a 36-year period, from 1907 to 1943.

This research study seeks to evaluate the techno-economic and environmental implications of a variety of aero-derivative marine gas turbine cycles that have been modelled for the propulsion of different types of merchant ships. It involves the installation and operation of gas turbine propulsion systems in different marine environmental conditions and aims to evaluate the effect of the aerodynamic and hydrodynamic variations expected to be encountered by these ships when they navigate across different climates and oceans along selected fixed trade routes. A combination of simulation tools developed in Cranfield University at the Department of Power and Propulsion including the validated gas turbine modelling and simulation code called “Turbomatch” and the “APPEM” simulation code for the analysis and Prediction of exhaust pollutants have been used along with the ongoing development of an integrated marine gas turbine propulsion system simulation platform known as “Poseidon”. It is the main objective of this research to upgrade the competence level of “Poseidon” so as to facilitate the conduct of a variety of longer and more complex oceangoing voyage scenarios through the introduction of an ambient temperature variation numerical module. Expanding the existing code has facilitated the prediction of the effect of varying aerodynamic and hydrodynamic conditions that may be encountered by gas turbine propulsion systems when such ships navigate through unstable ocean environments along their fixed trade routes at sea. The consequences of operating the marine gas turbines under ideal weather conditions has been investigated and compared with a wide range of severe operating scenarios under unstable weather and sea conditions in combination with hull fouling has been assessed. The techno-economic and environmental benefits of intercooling/exhaust waste heat recuperation of the ICR model have been predicted through the evaluation of different ship propulsion performance parameters in a variety of voyage analysis leading to the prediction of fuel consumption quantities, emission of NOx, CO2, CO and UHCs and the estimation of the HPT blade life as well. The different gas turbine cycle configurations of the research were found to respond differently when operated under various environmental profiles of the ship’s trade route and the number of units for each model required to meet the power plant capacity in each scenario and for each ship was assessed. The study therefore adds to the understanding of the operating costs and asset management of marine gas turbine propulsion systems of any ocean carrier and in addition it reveals the economic potentials of using BOG as the main fuel for firing gas turbine propulsion plants of LNG Carriers.

When two or more individual materials combine to form a new material with improved characteristics, a composite is created. The two major components in a thermoplastic composite are the polymer, such as polypropylene (PP), and the filler, such as minerals like calcium carbonate and talc, or agricultural crop by-products like wheat straw, soy hull and soy stems. The main advantages of using agricultural fillers (AgFillers) in polypropylene are cost reduction and modulus improvement, without drastically increasing the specific gravity of the composite. These properties can be further enhanced by subjecting the composite to the bulk orientation process, in which the polymer chains align to give superior strength to the material, while the presence of polar AgFillers contributes to a reduction in material density. The objective of this research was to systematically study the relationships between the components and properties of AgFiller-PP composites, and their contributions to property modifications. Three types of AgFillers, wheat straw (WS), soy hulls (SH) and soy stems (SS) were studied, along with two PP types, virgin PP (vPP) and recycled PP (rPP), and mixtures of the two PP types. Non-oriented composites with a composition ratio of 40 wt% AgFiller to 60 wt% PP were tested for their morphology, chemical, thermal, rheological and mechanical properties. Similar properties of oriented composites with 20 wt% wheat straw filler and 80 wt% PP were also examined. The type of AgFiller was found to play a significant role in determining the rheological and mechanical properties of non-oriented AgFiller-PP composites. Scanning electron microscopy (SEM) showed that AgFillers had the tendancy to align lengthwise when subjected to the extrusion process. Depending on the fiber alignment within the filler with respect to the lengthwise direction of the filler, each AgFiller contributed differently to the composites’ properties. Stem-based AgFillers like WS and SS had fiber alignment parallel to the lengthwise direction, and the composites created had higher viscosity and higher flexural modulus. On the other hand, shell-based AgFillers like SH had fiber alignment perpendicular to the filler’s length, and were found to have less contribution to viscosity increase. Fourier transform Infrared (FTIR) spectroscopy using attenuated total reflectance (ATR) technique showed that a skin layer of PP congregated on the surface of all the non-oriented AgFiller-PP composites, regardless of the AgFiller used. The main contribution of PP polymer type was to the rheological properties of non oriented AgFiller-PP composites. The presence of rPP also appeared to slightly improve the immiscibility between polar AgFillers and nonpolar PP polymer, according to SEM image analysis. The viscosity of the composites decreased linearly with increasing amount of rPP, because the rPP tested had significantly lower viscosity than the vPP chosen. No statistically significant conclusions could be drawn on the mechanical property changes due to large experimental variance that existed in the data. Bulk orientation of AgFiller-PP composites was shown to provide significant reduction in the material’s density as well as improvement in physical properties. Experimental results of oriented wheat straw-PP composites showed that wheat straw was highly comparable, perhaps even more superior, to wood fibers as filler for oriented PP composites. The ability to produce oriented wheat straw-PP composites using the same technology and conditions as producing oriented wood-plastic composites affirmed the feasibility for commercialization of oriented wheat straw-PP composites, and by means contributing to setting a milestone in the scientific research of AgFiller-thermoplastic biocomposites.

When two or more individual materials combine to form a new material with improved characteristics, a composite is created. The two major components in a thermoplastic composite are the polymer, such as polypropylene (PP), and the filler, such as minerals like calcium carbonate and talc, or agricultural crop by-products like wheat straw, soy hull and soy stems. The main advantages of using agricultural fillers (AgFillers) in polypropylene are cost reduction and modulus improvement, without drastically increasing the specific gravity of the composite. These properties can be further enhanced by subjecting the composite to the bulk orientation process, in which the polymer chains align to give superior strength to the material, while the presence of polar AgFillers contributes to a reduction in material density. The objective of this research was to systematically study the relationships between the components and properties of AgFiller-PP composites, and their contributions to property modifications. Three types of AgFillers, wheat straw (WS), soy hulls (SH) and soy stems (SS) were studied, along with two PP types, virgin PP (vPP) and recycled PP (rPP), and mixtures of the two PP types. Non-oriented composites with a composition ratio of 40 wt% AgFiller to 60 wt% PP were tested for their morphology, chemical, thermal, rheological and mechanical properties. Similar properties of oriented composites with 20 wt% wheat straw filler and 80 wt% PP were also examined. The type of AgFiller was found to play a significant role in determining the rheological and mechanical properties of non-oriented AgFiller-PP composites. Scanning electron microscopy (SEM) showed that AgFillers had the tendancy to align lengthwise when subjected to the extrusion process. Depending on the fiber alignment within the filler with respect to the lengthwise direction of the filler, each AgFiller contributed differently to the composites’ properties. Stem-based AgFillers like WS and SS had fiber alignment parallel to the lengthwise direction, and the composites created had higher viscosity and higher flexural modulus. On the other hand, shell-based AgFillers like SH had fiber alignment perpendicular to the filler’s length, and were found to have less contribution to viscosity increase. Fourier transform Infrared (FTIR) spectroscopy using attenuated total reflectance (ATR) technique showed that a skin layer of PP congregated on the surface of all the non-oriented AgFiller-PP composites, regardless of the AgFiller used. The main contribution of PP polymer type was to the rheological properties of non oriented AgFiller-PP composites. The presence of rPP also appeared to slightly improve the immiscibility between polar AgFillers and nonpolar PP polymer, according to SEM image analysis. The viscosity of the composites decreased linearly with increasing amount of rPP, because the rPP tested had significantly lower viscosity than the vPP chosen. No statistically significant conclusions could be drawn on the mechanical property changes due to large experimental variance that existed in the data. Bulk orientation of AgFiller-PP composites was shown to provide significant reduction in the material’s density as well as improvement in physical properties. Experimental results of oriented wheat straw-PP composites showed that wheat straw was highly comparable, perhaps even more superior, to wood fibers as filler for oriented PP composites. The ability to produce oriented wheat straw-PP composites using the same technology and conditions as producing oriented wood-plastic composites affirmed the feasibility for commercialization of oriented wheat straw-PP composites, and by means contributing to setting a milestone in the scientific research of AgFiller-thermoplastic biocomposites.

In the current water resources scientific literature, a wide variety of engineering design problems are solved in a simulation-optimization framework. These problems can have single or multiple objective functions and their decision variables can have discrete or continuous values. The majority of current literature in the field of water resources systems optimization report using heuristic global optimization algorithms, including evolutionary algorithms, with great success. These algorithms have multiple parameters that control their behavior both in terms of computational efficiency and the ability to find near globally optimal solutions. Values of these parameters are generally obtained by trial and error and are case study dependent. On the other hand, water resources simulation-optimization problems often have computationally intensive simulation models that can require seconds to hours for a single simulation. Furthermore, analysts may have limited computational budget to solve these problems, as such, the analyst may not be able to spend some of the computational budget to fine-tune the algorithm settings and parameter values. So, in general, algorithm parsimony in the number of parameters is an important factor in the applicability and performance of optimization algorithms for solving computationally intensive problems. A major contribution of this thesis is the development of a highly efficient, single objective, parsimonious optimization algorithm for solving problems with discrete decision variables. The algorithm is called Hybrid Discrete Dynamically Dimensioned Search, HD-DDS, and is designed based on Dynamically Dimensioned Search (DDS) that was developed by Tolson and Shoemaker (2007) for solving single objective hydrologic model calibration problems with continuous decision variables. The motivation for developing HD-DDS comes from the parsimony and high performance of original version of DDS. Similar to DDS, HD-DDS has a single parameter with a robust default value. HD-DDS is successfully applied to several benchmark water distribution system design problems where decision variables are pipe sizes among the available pipe size options. Results show that HD-DDS exhibits superior performance in specific comparisons to state-of-the-art optimization algorithms. The parsimony and efficiency of the original and discrete versions of DDS and their successful application to single objective water resources optimization problems with discrete and continuous decision variables motivated the development of a multi-objective optimization algorithm based on DDS. This algorithm is called Pareto Archived Dynamically Dimensioned Search (PA-DDS). The algorithm parsimony is a major factor in the design of PA-DDS. PA-DDS has a single parameter from its search engine DDS. In each iteration, PA-DDS selects one archived non-dominated solution and perturbs it to search for new solutions. The solution perturbation scheme of PA-DDS is similar to the original and discrete versions of DDS depending on whether the decision variable is discrete or continuous. So, PA-DDS can handle both types of decision variables. PA-DDS is applied to several benchmark mathematical problems, water distribution system design problems, and water resources model calibration problems with great success. It is shown that hypervolume contribution, HVC1, as defined in Knowles et al. (2003) is the superior selection metric for PA-DDS when solving multi-objective optimization problems with Pareto fronts that have a general (unknown) shape. However, one of the main contributions of this thesis is the development of a selection metric specifically designed for solving multi-objective optimization problems with a known or expected convex Pareto front such as water resources model calibration problems. The selection metric is called convex hull contribution (CHC) and makes the optimization algorithm sample solely from a subset of archived solutions that form the convex approximation of the Pareto front. Although CHC is generally applicable to any stochastic search optimization algorithm, it is applied to PA-DDS for solving six water resources calibration case studies with two or three objective functions. These case studies are solved by PA-DDS with CHC and HVC1 selections using 1,000 solution evaluations and by PA-DDS with CHC selection and two popular multi-objective optimization algorithms, AMALGAM and ε-NSGAII, using 10,000 solution evaluations. Results are compared based on the best case and worst case performances (out of multiple optimization trials) from each algorithm to measure the expected performance range for each algorithm. Comparing the best case performance of these algorithms shows that, PA-DDS with CHC selection using 1,000 solution evaluations perform very well in five out of six case studies. Comparing the worst case performance of the algorithms shows that with 1,000 solution evaluations, PA-DDS with CHC selection perform well in four out of six case studies. Furthermore, PA-DDS with CHC selection using 10,000 solution evaluations perform comparable to AMALGAM and ε-NSGAII. Therefore, it is concluded that PA-DDS with CHC selection is a powerful optimization algorithm for finding high quality solutions of multi-objective water resources model calibration problems with convex Pareto front especially when the computational budget is limited.

Tie-down systems are used to fasten drilling rigs to the deck of offshore structures during harsh environmental conditions such as hurricanes. During Hurricane Ivan (2004) and Katrina (2005), a number of offshore structures were moved and several tie-down systems were damaged. In the present study, the reaction force and connection capacity of tie-down systems for a TLP and SPAR are investigated. The environmental conditions are taken from the API Bulletin 2INT-MET which has been updated after several major storms during 2004-2005. The hydrodynamic coefficients of the TLP and SPAR are obtained using a 3D diffraction/radiation panel method. The motions of the TLP and SPAR are then simulated in the time domain by using the hull-mooring-riser coupled dynamic analysis tool CHARM3D. Based on the simulated motion and acceleration time series, the inertial and gravity loads on derrick and skid base footing are calculated. In addition to the inertial-gravity loads, wind forces exerted on the derrick are also calculated. All the external forces and resultant hull motions are simulated for 100-year, 200-year and 1000-year storms to observe the derrick structural integrity with increasing environmental intensity. Various environmental headings are also considered to find the maximum reaction forces. In the present method, the phase differences between gravity-inertia forces and wind forces are taken into consideration to obtain more realistic loads on derrick and skid base footings. This research shows that the maximum and minimum load values are appreciably higher for the SPAR. In addition, the direction of external forces is also important to determine maximum reaction forces on footings. The capacities of the clamps in slip, bolt tension, and bolt shear can be also analyzed using the resultant data to provide guidance on appropriate design values.