The theme of this dissertation is Ricardian equivalence, and its objective is to examine the effects of government debt on private consumption expenditures (Essay One), on interest rates (Essay Two), on the current account balance (Essay Three), and on individual intertemporal decision-making (Essay Four). The effects of government debt are important if debt is neutral (e.g., if “Ricardian equivalence” holds), then a stabilization program that is based on demand management policy to curtail fiscal deficits will not be operative. On the other hand, if debt is not neutral (or if Ricardian equivalence does not hold), then deficit finance may induce private consumption, boost interest rates, crowd out investment, and retard economic growth. Essay One contributes to the existing literature by taking into account the nature of liquidity constraints in a developing economy in an aggregate consumption function. Previous empirical tests on Ricardian equivalence have not considered the role of a dominant resource aspect of a country. Essay Two and Essay Three incorporate a dominant resource aspect in Indonesia by estimating the oil-macroeconomic relationship. Furthermore, Essay Three takes into account the role of capital inflows by including debt securities. Essay Four uses experimental economics methods to examine the role of distortionary taxes on Ricardian equivalence. There have been only a few studies that use an experimental approach to examine the effect of deficit spending on consumption expenditures, but these existing experimental studies ignore the role of distortionary taxes in affecting subjects’ consumption-saving decisions and focus on the presence of liquidity constraints, myopia, and uncertainty on future income. Essay Four contributes to the Ricardian equivalence literature by taking into account distortionary taxes in a Ricardian institution by levying taxes on savings in an intertemporal individual consumption-savings decision in laboratory experiments. By utilizing the aggregate consumption function and the Euler equation consumption function, Essay One shows that Indonesian consumers tend to behave in a non-Ricardian way. Public debt most likely will lead to crowding out of investment, and will retard capital accumulation and economic growth. The extent to which individuals perceive government expenditures as complements for their consumption is substantial. An increase in government expenditures will increase the marginal utility of private consumption and has an expansionary effect on aggregate demand. The complementarity between private consumption and government expenditures may be partly due to the allocation of government subsidies to basic goods and services such as electricity, fuel, fertilizer, health centers, and education. Liquidity constraints may cause consumption to have an excess sensitivity to income. The short-run and long-run aggregate consumption function estimates show that income affects consumption, indicating that consumers follow a “rule of thumb” of consuming their current income. A high ratio of public debt to gross domestic product (GDP) in Indonesia may also be the culprit of the excess sensitivity of private consumption to income. Due to low salaries in the formal sector, employees have been engaged in moonlighting activities, mostly in the form of self-employment (e.g., opening retail stores or services). This phenomenon may help to explain why private credit−which amounts to 29 percent of GDP−fails to explain consumption behavior. Most loans are made for investment rather than for consumption. Consumers’ behavior is insensitive to taxation, which perhaps is due to the fact that tax enactment is not explicitly revealed in Indonesia (e.g., price tags in the supermarket include the sales tax, and employees are only informed about their after-tax net wage instead of their gross wage). The share of tax collections to GDP averages only about 15 percent. There is still a large portion of the population who do not pay taxes or who pay far below what they should pay. The fiscal authority needs to focus more attention on alternative financing, i.e. taxation, whose system is essential to be enhanced. Essay Two shows that by excluding oil prices, deficits and debt significantly increase the real interest rate, thereby invalidating Ricardian equivalence. The evidence shows some preference for debt and deficit over government expenditures as determinants of interest rates. Inclusion of the oil price weakens the Neoclassical results, providing more support for the Ricardian paradigm. Deficits no longer increase interest rates, yet debt still significantly increases interest rates. This result reflects a loss of momentum for the Indonesian government two decades ago to decrease its dependency on debt. The government could have used the windfall oil revenue to pay off foreign debt; instead, the windfall was spent on import-intensive infrastructure development projects, in order to build domestic industry and to subsidize rice and petroleum products. The importance of oil prices in the interest rate estimation suggests that in modeling the Indonesian macroeconomy, the oil sector should be incorporated. The non-stationary nature of the stock of debt implies the failure of intertemporal budget balance to hold, indicating that the debt-financed deficit is unsustainable. Essay Three shows that around 80 percent of the estimation results provide support for the Neoclassical view, a result that is consistent with the twin deficits hypothesis. The long-run estimates indicate an almost one-to-one relationship between the government budget and the trade balance, while the short-run estimates show a smaller magnitude. When capital inflows are included, the twin deficits phenomenon is less pronounced in the short-run and disappears in the long-run. An increase in the oil price statistically and significantly improves the trade balance in the short-run and in the long-run. Essay Four shows that subjects fully anticipate an increase in future taxation by increasing the amount bequeathed in one-to-one correspondence to the increase in debt. Even under a Ricardian institution, the distorting nature of taxes on savings alters subjects’ consumption-savings decisions. The equality of the change in bequests and the change in deficit spending is not attained under the savings taxes treatment, invalidating Ricardian equivalence. In line with the results of Essays One, Two, and Three, which suggest the vital need to enhance the taxation system, the results of Essay Four entail the importance of taxes on interest income in Indonesia.

In this study, acoustic noise radiation through a duct in frequency domain is analyzed. Frequency domain linearized Euler equations are solved for turbofan exhaust noise propagation and radiation. The geometry in studied cases is assumed as axisymmetric. The acoustic waves are decomposed into periodic azimuthal modes. Characteristic boundary conditions, and buffer zone boundary conditions are employed. Iterative type pseudo time integration is employed. Nonuniform background flow effect on the radiation pattern is experienced. All computations are performed in parallel using MPI library routines in computer cluster. Results proved that the one with the buffer zone has a better radiation characteristic than the characteristic one because of absorbtion of spurious waves. It is seen that the efficiency of the buffer zone is frequency dependent.

Cette thèse porte sur l’analyse mathématique de l’interaction d’un fluide non-visqueux avec des structures immergées. Plus précisément, elle est structurée autour de deux axes principaux. L’un d’eux est l’analyse asymptotique du mouvement d’une particule infinitésimale en milieu liquide. L’autre concerne l’interaction entre des vagues et une structure immergée. La première partie de la thèse repose sur l’analyse mathématique d’un système d’équations différentielles ordinaires non-linéaires d’ordre 2 modélisant le mouvement d’un solide infiniment petit dans un fluide incompressible en 2D. Les inconnues du modèle décrivent la position du solide, c’est-à-dire la position du centre de masse et son angle de rotation. Les équations proviennent de la deuxième loi de Newton avec un prototype de force de type Kutta-Joukowski. Plus précisément, nous étudions la dynamique de ce système lorsque l’inertie du solide tend vers 0. Les principaux outils utilisés sont des développements asymptotiques multiéchelles en temps. Pour la dynamique de la position du centre de masse, l’étude met en évidence des analogies avec le mouvement d’une particule chargée dans un champ électromagnétique et la théorie du centre-guide. En l’occurrence, le mouvement du centreguide est donné par une équation de point-vortex. La dynamique de l’angle est quant à elle donnée par une équation de pendule non-linéaire lentement modulée. Des régimes très différents se distinguent selon les données initiales. Pour de petites vitesses angulaires initiales la méthode de Poincaré-Lindstedt fait apparaitre une modulation des oscillations rapides, alors que pour de grandes vitesses angulaires initiales, un movement giratoire bien plus irrégulier est observé. C’est une conséquence particulière et assez spectaculaire de l’enchevêtrement des trajectoires homocliniques. La deuxième partie de la thèse porte sur le problème des vagues dans le cas où le domaine occupé par le fluide est à surface libre et avec un fond plat sur lequel un objet solide se translate horizontalement sous l’effet des forces de pression du fluide. Nous avons étudié deux systèmes asymptotiques qui décrivent le cas d’un fluide parfait incompressible en faible profondeur. Ceux-ci correspondent respectivement aux équations de Saint-Venant et de Boussinesq. Grâce à leur caractère bien-posé en temps long, les modèles traités permettent de prendre en compte certains effets de la mécanique du solide, comme les forces de friction, ainsi que les effets non-hydrostatiques. Notre analyse théorique a été complétée par des études numériques. Nous avons développé un schéma de différences finies d’ordre élevé et nous l’avons adapté à ce problème couplé afin de mettre en évidence les effets d’un solide (dont le mouvement est limité à des translations sur le fond) sur les vagues qui passent au dessus de lui. A la suite de ces travaux, nous avons souligné l’influence des forces de friction sur ce genre de systèmes couplés ainsi que sur le déferlement des vagues. Quant à l’amortissement dû aux effets hydrodynamiques, une vague ressemblance avec le phénomène de l’eau morte est mise en évidence. / This PhD thesis concerns the mathematical analysis of the interaction of an inviscid fluid with immersed structures. More precisely it revolves around two main problems: one of them is the asymptotic analysis of an infinitesimal immersed particle, the other one being the interaction of water waves with a submerged solid object. Concerning the first problem, we studied a system of second order non-linear ODEs, serving as a toy model for the motion of a rigid body immersed in a two-dimensional perfect fluid. The unknowns of the model describe the position of the object, that is the position of its center of mass and the angle of rotation; the equations arise from Newton’s second law with the consideration of a Kutta-Joukowski type lift force. It concerns the detailed analysis of the dynamic of this system when the solid inertia tends to 0. For the evolution of the position of the solid’s center of mass, the study highlights similarities with the motion of a charged particle in an electromagnetic field and the wellknown “guiding center approximation”; it turns out that the motion of the corresponding guiding center is given by a point-vortex equation. As for the angular equation, its evolution is given by a slowly-in-time modulated non-linear pendulum equation. Based on the initial values of the system one can distinguish qualitatively different regimes: for small angular velocities, by the Poincaré-Lindstedt method one observes a modulation in the fast time-scale oscillatory terms, for larger angular velocities however erratic rotational motion is observed, a consequence of Melnikov’s observations on the presence of a homoclinic tangle. About the other problem, the Cauchy problem for the water waves equations is considered in a fluid domain which has a free surface on the upper vertical limit and a flat bottom on which a solid object moves horizontally, its motion determined by the pressure forces exerted by the fluid. Two shallow water asymptotic regimes are detailed, well-posedness results are obtained for both the Saint-Venant and the Boussinesq system coupled with Newton’s equation characterizing the solid motion. Using the particular structure of the coupling terms one is able to go beyond the standard scale for the existence time of solutions to the Boussinesq system with a moving bottom. An extended numerical study has also been carried out for the latter system. A high order finite difference scheme is developed, extending the convergence ratio of previous, staggered grid based models. The discretized solid mechanics are adapted to represent important features of the original model, such as the dissipation due to the friction term. We observed qualitative differences for the transformation of a passing wave over a moving solid object as compared to an immobile one. The movement of the solid not only influences wave attenuation but it affects the shoaling process as well as the wave breaking. The importance of the coefficient of friction is also highlighted, influencing qualitative and quantitative properties of the coupled system. Furthermore, we showed the hydrodynamic damping effects of the waves on the solid motion, reminiscent of the so-called dead water phenomenon.

The present work makes a study of the drag forces of umbilical cables of pipes inspection robots and aims to determine a valid model for their calculation. For this purpose, the physical models are developed in relation to the friction forces for the straight and curved sections in all their possible configurations, obtaining for each case a differential equation that models the friction phenomenon and that includes fluid and cable the characteristics. By solving the differential equation, an explicit expression is obtained for the value of the frictional force in each case. In the present work, the obtained model is evaluated in comparison with the traditional simplified model. It is also presented a study about the influence of the stiffness of the cable and how this characteristic generates the forces of the normal general forces at the ends of the curves that, finally, result in an additional component of the frictional forces. By comparison with actual drag force measurements, the model obtained is validated. The complexity of the calculations required for the determination of the pull forces in real pipes makes it necessary to use software tools to facilitate it. For this reason, two software applications are developed, one specific for rigid pipes and another one for flexible pipes. A series of strategies of how to keep low the maximum value of the cable tension are presented too. / El presente trabajo se dedica al estudio de fuerzas de arrastre de cables umbilicales de robot de inspección o desobstrucción de tuberías y tiene como objetivo la determinación de un modelo válido para el cálculo de las mismas. Para tal fin, se desarrollan los modelos físicos en relación a las fuerzas de rozamiento presentes para tramos rectos y curvas en todas sus configuraciones posibles, obteniéndose así, para cada caso, una ecuación diferencial que modela el fenómeno del rozamiento y que incluye las variables propias del fluido presente y las características pertinentes del cable. Mediante la resolución de esa ecuación diferencial, se obtiene una expresión explícita para el valor de la fuerza de rozamiento en cada caso. En el presente trabajo, el modelo obtenido es evaluado mediante comparación con el modelo simplificado tradicional de manera de ver los alcances del nuevo modelo. Se realiza también una presentación de la influencia que tiene la rigidez del cable y como esta rigidez a la flexión genera fuerzas normales adicionales en los extremos de las curvas que redundan finalmente en una componente adicional de las fuerzas de fricción. Mediante comparación con mediciones reales de fuerza de arrastre se valida el modelo obtenido Dada la complejidad de los cálculos requeridos para la determinación de las fuerzas de arrastre de tuberías reales se desarrollan dos aplicaciones de software para el cálculo de las mismas, una específica para tuberías rígidas y otra para tuberías flexibles utilizando algoritmos de cálculo basados en las ecuaciones determinadas. Son presentadas también, una serie de estrategias de forma de mantener acotado el valor máximo de la tensión de cable. Dentro de las estrategias están la elección de materiales de recubrimiento de cable que presenten un bajo coeficiente de fricción con la tubería, la adopción de cables cuyo peso específico sea tal que el peso se iguale a la fuerza de empuje y la incorporación de varios dispositivos de tracción del cable de modo de mantener bajas las contra tensiones del cable utilizando un sistema distribuido de empuje.

The present work makes a study of the drag forces of umbilical cables of pipes inspection robots and aims to determine a valid model for their calculation. For this purpose, the physical models are developed in relation to the friction forces for the straight and curved sections in all their possible configurations, obtaining for each case a differential equation that models the friction phenomenon and that includes fluid and cable the characteristics. By solving the differential equation, an explicit expression is obtained for the value of the frictional force in each case. In the present work, the obtained model is evaluated in comparison with the traditional simplified model. It is also presented a study about the influence of the stiffness of the cable and how this characteristic generates the forces of the normal general forces at the ends of the curves that, finally, result in an additional component of the frictional forces. By comparison with actual drag force measurements, the model obtained is validated. The complexity of the calculations required for the determination of the pull forces in real pipes makes it necessary to use software tools to facilitate it. For this reason, two software applications are developed, one specific for rigid pipes and another one for flexible pipes. A series of strategies of how to keep low the maximum value of the cable tension are presented too. / El presente trabajo se dedica al estudio de fuerzas de arrastre de cables umbilicales de robot de inspección o desobstrucción de tuberías y tiene como objetivo la determinación de un modelo válido para el cálculo de las mismas. Para tal fin, se desarrollan los modelos físicos en relación a las fuerzas de rozamiento presentes para tramos rectos y curvas en todas sus configuraciones posibles, obteniéndose así, para cada caso, una ecuación diferencial que modela el fenómeno del rozamiento y que incluye las variables propias del fluido presente y las características pertinentes del cable. Mediante la resolución de esa ecuación diferencial, se obtiene una expresión explícita para el valor de la fuerza de rozamiento en cada caso. En el presente trabajo, el modelo obtenido es evaluado mediante comparación con el modelo simplificado tradicional de manera de ver los alcances del nuevo modelo. Se realiza también una presentación de la influencia que tiene la rigidez del cable y como esta rigidez a la flexión genera fuerzas normales adicionales en los extremos de las curvas que redundan finalmente en una componente adicional de las fuerzas de fricción. Mediante comparación con mediciones reales de fuerza de arrastre se valida el modelo obtenido Dada la complejidad de los cálculos requeridos para la determinación de las fuerzas de arrastre de tuberías reales se desarrollan dos aplicaciones de software para el cálculo de las mismas, una específica para tuberías rígidas y otra para tuberías flexibles utilizando algoritmos de cálculo basados en las ecuaciones determinadas. Son presentadas también, una serie de estrategias de forma de mantener acotado el valor máximo de la tensión de cable. Dentro de las estrategias están la elección de materiales de recubrimiento de cable que presenten un bajo coeficiente de fricción con la tubería, la adopción de cables cuyo peso específico sea tal que el peso se iguale a la fuerza de empuje y la incorporación de varios dispositivos de tracción del cable de modo de mantener bajas las contra tensiones del cable utilizando un sistema distribuido de empuje.

No description available.

Ce travail est consacré à l’étude numérique de l’interaction entre un fluide compressible et une structure indéformable, en adaptant une famille récente de schémas d’ordre très élevé à la prise en compte de conditions aux bords particulières entre le fluide et la structure. Plus précisément,on évalue l’apport de schémas d’ordre strictement supérieur à 3 par rapport à des stratégies plus classiques dans la littérature restreintes aux ordres 1 et 2. Un résultat important est qu’il est possible de réaliser le couplage à tout ordre et qu’il existe des configurations pour lesquelles on observe un gain important pour les ordres élevés. Une revue bibliographique est faite rappelant les résultats théoriques concernant les systèmes hyperboliques et décrivant les méthodes utilisées dans la littérature pour la simulation de la dynamique des gaz et la prise en compte des conditions aux bords. Un schéma sur grilles cartésiennes décalées et d’ordre très élevé est proposé pour la résolution des équations d’Euler en 1D/2D. Ce schéma est basé sur le formalisme Lagrange-projection et bien que formulé en énergie interne assure conservation et consistance faible grâce à un correctif en énergie interne. Parallèlement, l’étude pour les systèmes hyperboliques linéaires de discrétisation à l’ordre très élevé des conditions aux bords est faite. Elle met en évidence la nécessité pour l’ordre élevé de s’intéresser à la stabilité des schémas ainsi obtenus. À partir de ces travaux, la prise en compte de conditions aux bords en vitesse normale imposée est réalisée pour les équations d’Euler en 1D et 2D. Enfin, une procédure de couplage entre fluide compressible et structure indéformable est proposée. / This work is devoted to the construction of stable and high-order numerical methods in order to simulate fluid - rigid body interactions. In this manuscript, a bibliographic overview is done, which highlights theoretical results about hyperbolic system of conservation laws, as well as the methods available in the literature for the hydrodynamics simulation and the numericalboundary treatment. A high-order accurate scheme is proposed on staggered Cartesian grids to approximate the solution of Euler equations in 1D and 2D. The scheme relies on Lagrange-remap formalism, and although formulated in internal energy, ensures both conservation and weak consistency thanks to an internal energy corrector. In the same time, the study of high-order numerical boundary treatment for linear hyperbolic system is done. It highlights the necessity to focus especially on the linear stability of the effective scheme. Starting from the linear results, the numerical boundary treatment with imposed normal velocity is done for Euler equations in 1D and 2D. Last, the coupling between a compressible fluid and a rigid body is realized, using the designed procedure for numerical boudary treatment.

his diploma thesis deals with hydraulic design of vane wheel impeller of wide range Francis turbine; in addition to hydraulic calculation it consists overview of used theory, modelling in SolidWorks and computing in Fluent.

Cette thèse porte sur le problème de transport optimal incompressible, un problème introduit par Brenier à la fin des années 80 dans le but de décrire l’évolution d’un fluide incompressible et non-visqueux de façon lagrangienne, ou autrement dit en fixant l’état initial et l’état final de ce fluide, et en minimisant une certaine fonctionnelle sur un ensemble de dynamiques admissibles. Ce manuscrit contient deux parties.Dans la première, on étudie la dépendance du problème de transport optimal incompressible par rapport aux données. Plus précisément, on étudie la dépendance du champ de pression (le multiplicateur de Lagrange associé à la contrainte d’incompressibilité) par rapport à la mesure γ prescrivant l’état initial et l’état final du fluide. On montre au Chapitre 2 par des méthodes variationnelles que le gradient de la pression, en tant qu’élément d’un espace proche du dual des fonctions C^1, dépend de γ de façon hölderienne pour la distance de Monge-Kantorovic. En contrepartie, on montre au Chapitre 4 que pour tout r > 1, le champ de pression dans l'espace de Lebesgue L^r_t L^1_x ne peut pas être une fonction lipschitzienne de γ. Ce résultat est lié au caractère mal-posé de l’équation d’Euler cinétique, une équation cinétique s’interprétant comme l’équation d’optimalité dans le problème de transport optimal incompressible, à laquelle le Chapitre 3 de cette thèse est dédié.Dans une seconde partie, on s’intéresse à la régularisation entropique du problème de transport optimal incompressible, introduit par Arnaudon, Cruzeiro, Léonard et Zambrini en 2017 sous le nom de problème de Brödinger. On prouve au Chapitre 5 que comme dans le cas du transport optimal incompressible, on peut associer à toute solution un champ scalaire de pression agissant comme multiplicateur de Lagrange pour la contrainte d’incompressibilité. On montre ensuite au Chapitre 6 que lorsque le paramètre de régularisation tend vers zéro, le problème de Brödinger converge vers le problème de transport optimal incompressible au sens de la Γ-convergence, et avec convergence des champs de pression. Ce dernier chapitre est issu d'un travail effectué en collaboration avec L. Monsaingeon. / This thesis focuses on Incompressible Optimal Transport, a minimization problem introduced by Brenier in the late 80's, aiming at describing the evolution of an incompressible and inviscid fluid in a Lagrangian way , i.e. by prescribing the state of the fluid at the initial and final times and by minimizing some functional among the set of admissible dynamics. This text is divided into two parts.In the first part, we study the dependence of this optimization problem with respect to the data. More precisely, we analyse the dependence of the pressure field, the Lagrange multiplier corresponding to the incompressibility constraint, with respect to the endpoint conditions, described by a probability measure γ determining the state of the fluid at the initial and final times. We show in Chapter 2 by purely variational methods that the gradient of the pressure field, as an element of a space that is close to the dual of C^1, is a Hölder continuous function of γ for the Monge-Kantorovic distance. On the other hand, we prove in Chapter 4 that for all r>1 the pressure field, as an element of L^r_t L^1_x, cannot be a Lipschitz continuous function of γ for the Monge-Kantorovic distance. This last statement is linked to an ill-posedness result proved in Chapter 3 for the so-called kinetic Euler equation, a kinetic PDE interpreted as the optimality equation of the Incompressible Optimal Transport problem.In the second part, we are interested in the entropic regularization of the Incompressible Optimal Transport problem: the so-called Brödinger problem, introduced by Arnaudon, Cruzeiro, Léonard and Zambrini in 2017. On the one hand, we prove in Chapter 5 that similarly to what happens in the Incompressible Optimal Transport case, to a solution always corresponds a scalar pressure field acting as the Lagrange multiplier for the incompressibility constraint. On the other hand, we prove in Chapter 6 that when the diffusivity coefficient tends to zero, the Brödinger problem converges towards the Incompressible Optimal Transport problem in the sense of Gamma-convergence, and with convergence of the pressure fields. The results of Chapter 6 come from a joint work with L. Monsaingeon.

No description available.