Dans le chapitre 1, j'examine l'impact des politiques de taxation qui favorisent les entreprises à faible chiffre d'affaires (en dessous d'un certain seuil d'imposition) sur la production globale. Au Cameroun, les entreprises dont le chiffre d'affaires est inférieur au seuil d'imposition paient une taxe forfaitaire ne dépassant pas 1% du chiffre d'affaires. Les entreprises dont le chiffre d'affaires dépasse le seuil d'imposition doivent s'acquitter d'un impôt proportionnel sur les bénéfices dont le taux était de 38,5% en 2008. Les données du Recensement général des entreprises du Cameroun de 2008 exhibent une concentration des entreprises au seuil d'imposition de 15 millions XAF. Ceci est cohérent avec le fait que cette politique de taxation peut théoriquement conduire à des distorsions qui entraînent certaines entreprises à embaucher moins de travailleurs que d'autres moins productives qu'elles afin de rester au seuil d'imposition et d'éviter de payer des impôts importants. Je développe un modèle basé sur le modèle de Hopenhayn (1992) de dynamique des firmes prenant en compte la taxation des entreprises. Je trouve un intervalle critique pour la productivité dans lequel la demande de main-d'oeuvre diminue à mesure que la productivité augmente. Le modèle est calibré avec les données camerounaises de 2008. Comme résultat, la production globale augmente de 4\% lorsqu'un impôt proportionnel uniforme sur les bénéfices est utilisé à la place de la taxe existante, et de 17\% lorsqu'un impôt forfaitaire uniforme est utilisé, pour les mêmes recettes fiscales. Je mène des expériences de politiques basées sur des politiques d'imposition similaires présentes dans d'autres pays en développement tels que la Côte d'Ivoire et le Mali en Afrique de l'Ouest, et le Gabon et le Congo en Afrique centrale. Je trouve un impact positif sur la production agrégée lorsque le seuil d'imposition baisse de manière significative (pour les mêmes recettes fiscales) ou lorsque l'impôt payé par les entreprises juste en dessous du seuil se rapproche de celui payé par les entreprises juste au-dessus du seuil d'imposition. Dans le chapitre 2, j'étudie l'effet de l'utilisation du réseau social dans la recherche d'emploi sur les résultats agrégés. Empiriquement, à partir des donnée camerounaises de 2010, je mets en évidence l'association de l'utilisation des réseaux sociaux à des niveaux de salaires plus bas et à des emplois de moindre qualité. Je développe un modèle de recherche et d'appariement dans lequel les travailleurs sont hétérogènes dans leur réseau social et les entreprises sont hétérogènes dans l'emploi qu'elles ouvrent (qualifiés vs non qualifiés). Je trouve qu'il y a une pénalité salariale provenant de la possibilité rechercher un autre emploi quand on est employé. Cette pénalité salariale est plus élevée pour les travailleurs ayant un plus grand réseau social. Elle pourrait dominer l'effet positif d'avoir un plus grand réseau social sur le salaire, et conduire les travailleurs ayant un plus grand réseau social à avoir un salaire plus faible. Le chapitre 3 décrit une économie dans laquelle la taxe est prélevée à deux niveaux : le niveau du pays et le niveau de l'État. L'impôt au niveau de l'État peut également être considéré comme un impôt local pour les pays qui ne sont pas administrativement divisés en États. Le décideur au niveau de l'état doit tenir compte de la politique au niveau du pays lorsqu'il définit sa propre politique. Il peut choisir d'imposer avec ou sans déduction. Je développe un modèle de dynamique de firmes basé sur Hopenhayn (1992) augmenté pour prendre en compte la taxation à deux niveaux : le pays et l'état. Le modèle à calibré à l'économie américaine et des expériences numériques sont menées. J'analyse le cas des taxes sur les sorties au niveau des pays et des États. Je trouve que les résultats optimaux sont les mêmes avec et sans déduction, à l'exception des valeurs élevées de la taxe au niveau des pays. Aussi, prélever la taxe sur les facteurs donc le prix est flexible affecterait moins négativement la production agrégée. / In chapter 1, I examine the impact of tax policies that favorise low-turnover businesses (below a certain threshold of taxation) on aggregate output. Specifically, in Cameroon, the tax policy consists of a lumpsum tax of no more than 1% of sales for firms with sales below the taxation threshold; and firms with sales above the taxation threshold must pay a proportional profit tax, the rate of which was 38.5% in 2008. From the 2008 Cameroon General Business Census data, the concentration of businesses is right at the tax threshold of XAF 15 million. This is consistent with the fact that this tax policy can theoretically lead to size distortions that lead some firms to hire fewer workers than others who are less productive than them in order to remain at the tax threshold and avoid paying a large amount of tax. In a model based on the Hopenhayn (1992) model of firm dynamics extended to include taxation. I find a critical interval for productivity in which labor demand decreases as productivity increases. I calibrate the model with 2008 Cameroon data and find that aggregate output increases by 4% when a uniform proportional profit tax is used instead of the existing tax policy, and by 17% when a uniform lump sum tax is used, for the same tax revenue. I conduct policy experiments based on similar tax policies in other developing countries such as Côte d'Ivoire and Mali in West Africa, and Gabon and Congo in Central Africa. I find a positive impact on aggregate output when the threshold for taxation falls significantly (for the same tax revenue for the government) or when the tax paid by firms just below the threshold approaches that paid by firms just above the threshold for taxation. In Chapter 2, In the environment of a developing economy, I study the effect of the use of social networks in job search on aggregate outcomes. Empirically, I highlight some facts linking the use of social networks to average wages and job quality. I find that the use of social is associated with a lower wage. I also find that nonusers of social networks have better job quality (in terms of education accuracy, and benefitting training from the firm). I develop a model of search and matching in which workers are heterogenous in their social network and firms are heterogenous in the job they open (skilled vs unskilled). I find that there is a wage penalty coming from the presence of on-the-job search, and this wage penalty is higher for workers with higher social Networks. This penalty could dominate the positive effect of having a higher social network on wages, and lead workers with a higher social network to have lower wages. Chapter 3 describes an economy in which the tax is levied at two levels: The country level and the state level. The tax at the state level can also be seen as a local tax for countries that are not administratively divided into states. The policy-maker at the state level has to take into account the policy at the country level when setting his own policy. He can choose to tax with and without deduction. I develop a model of firm dynamic based on Hopenhayn (1992) augmented to take into account taxation two levels: the country and the state. I calibrate the Benchmark model to the US economy and I conduct numerical experiments. I analyze the case of output taxes at the country and state levels. I find that the optimal results are the same with and without deduction, except for the high values of the tax at the country level. I also for output tax at the country level, it looks more efficient to raise the tax at the state on the input with the more flexible price.

No abstract provided. / Thesis / Master of Engineering (MEngr) / Scope and contents: This thesis describes the behaviour of iron ore-water suspensions under turbulent flow conditions. This work is divided into two parts. Part I deals with the regimes of transport under steady state flow conditions in circular and horizontal ducts. The heterogeneous flow regime is extensively analyzed; a sequential discrimination of models with an oriented design of experiments have permitted the determination of the best model to correlate hydraulic gradients for these suspensions. A critical discussion on the limit deposit conditions is also included. Part II describes the behaviour of clear water under oscillatory flow conditions. The study demonstrates that the quasi-steady state hypothesis, i.e., fully developed flow assumption, applied to pulsatile turbulent flow under the conditions studied. Observations on the behaviour of iron ore-water suspensions under pulsatile flow are also included. The experiments were carried out using a new air-pulsing technique.

During the period 1967-1995, Swedish mental healthcare underwent a complete re-organisation, starting with county councils taking over responsibility for mental healthcare from the state. Asylums were then phased out and mental health care moved closer to patients. The Mental Health Reform of 1995 completed this decentralisation and put the emphasis on an independent and integrated life as a citizen in society and the idea of a dwelling of one’s own. This thesis describes and analyses spatial aspects of decentralised mental healthcare in Sweden, focusing on the decentralisation discourse regarding organisation, localisation, patient care and working methods behind decentralisation and its spatial performance. A case study of decentralised mental healthcare in Nacka, a Stockholm suburb, between 1958-1999 examines in particular the emerging decentralisation discourse 1958-1973, The Nacka Project 1974-1980 (one of the first examples of community care in Sweden), psychiatry in Nacka 1980-1994 and the official report Welfare and Freedom of Choice from 1995. The methods used include studies of documents, interviews, visual and architectural drawing analysis. The theoretical point of departure for the analysis is a post-structural heterogeneous concept of space where spatial materiality and discursiveness are looked upon as intertwined.    The result shows that the re-organisation of mental healthcare brought about a substantial spatial transformation. Normalisation of patients’ lives involved integration into society and support for independent living. The local environment was the main trope for the early stage of decentralised mental healthcare, but the notion of a dwelling of one’s own became the important trajectory to an independent life after 1995. The idea of the patient is challenged by the independence discourse, which could be said to contain an idea of the ‘non-patient’. Overall, it can be concluded that spatial organisations of the built environment are never value-free or neutral. They reflect, enable and constrain power relations in a society and material space can contribute to the power of one group at the expense of another. Furthermore, the results of the spatialities, or the meanings, cannot be predicted. It is therefore crucial to distinguish power in all its configurations and scales and to keep negotiations alive, especially within the field of mental healthcare, but also in the care sector as a whole and in other societal institutions where policies buildings and built environment interact with user practices. This kaleidoscopic perspective can be used for examining complexities in the past and present and for encouraging future potentialities in the process of making/enacting spatial relations. / QC 20120306

本文首先構建了在完全資訊下的異質分群模型。當玩家可以觀察其他玩家的類型，則均衡必定是非隔離的：大多數玩家將無意移動，這是因為他們的夥伴可以為他們帶來最好的報酬。均衡狀態將會是一個有效率的狀態。     然後，我們構建另一個分組模型:訊息不完全和雙重改變下的分群模型。結果表明，雖然非隔離的均衡有可能是在短期的穩定均衡，但只有隔離的均衡狀態可以在長期維持穩定。這是因為在長期下，大多數非隔離狀態可以輕易地切換到隔離狀態的緣故。 / This paper first constructs a grouping model with heterogeneous population under the setting of complete information. When player can observe other's type, the result isnon-segregation: most players have no intention to move and they can match with the one who brings them the best payoff in the original group. The equilibrium state is always efficient. We then construct another grouping model with incomplete information and double mutation. The result shows that, although non-segregation equilibria may emerge as stable equilibria in the short run, only segregation equilibria can be stochastically stable in the long run. This is because most of non-segregated states can switch to the others by the same re-sistance and some of them can easily switch to segregated state, but it is hard to switch back.

We describe heterogeneous multi-CPU and multi-GPU implementations of Jacobi's iterative method for the 2-D Poisson equation on a structured grid, in both single- and double-precision. Properly tuned, our best implementation achieves 98% of the empirical streaming GPU bandwidth (66% of peak) on a NVIDIA C1060. Motivated to find a still faster implementation, we further consider "wildly asynchronous" implementations that can reduce or even eliminate the synchronization bottleneck between iterations. In these versions, which are based on the principle of a chaotic relaxation (Chazan and Miranker, 1969), we simply remove or delay synchronization between iterations, thereby potentially trading off more flops (via more iterations to converge) for a higher degree of asynchronous parallelism. Our relaxed-synchronization implementations on a GPU can be 1.2-2.5x faster than our best synchronized GPU implementation while achieving the same accuracy. Looking forward, this result suggests research on similarly "fast-and-loose" algorithms in the coming era of increasingly massive concurrency and relatively high synchronization or communication costs.

The object of this thesis is to get a deeper understanding of the role of modulator agents in the synthesis of Zr- and Hf-based metal-organic frameworks (MOFs) and their impact on framework properties, such as textural properties, stability, hydrophobicity, and catalytic activity. For this purpose, MOFs are investigated that are built up by the commercially available linker 2,5-thiophenedicarboxylate and the Zr6(µ3-O)4(µ3-OH)412+ cluster. With proper choice of the modulator a new structure, namely DUT-126 (DUT = Dresden University of Technology), could be presented in the course of this work, besides the already known polymorphs of DUT-67, DUT-68 and DUT-69. Furthermore, DUT-67 is chosen as a model structure to functionalise the metal cluster of the framework by exchanging the modulator post-synthetically with hydrophobic fluorinated monocarboxylic acids. With the introduction of these fluorinated molecules, the surface polarities and the stability against water removal can be tuned. In addition, the metal clusters of DUT-67 were modified with a complete removal of the pristine modulator molecules by means of an acidic treatment in order to generate open metal sites that can function as Lewis acid sites. The suitability of DUT-67 and its acid treated analogues as heterogenous catalyst was tested on the Meerwein-Ponndorf-Verley reduction of cyclohexanone. Furthermore, the UiO-67 analogue DUT-122, which contains the luminescent linker 9-fluorenone-2,7-dicarboxylate, was tested as sensor material to detect solvent vapours. It could be shown that DUT-122 is sensitive to various solvent vapours, which induce photoluminescent shifts and intensity changes of the fluorescence emission profile depending on the polarity and the functionality of the respective solvent.

La capacité à déterminer les structures moléculaires en trois dimensions à partir de monocristaux par des méthodes de diffraction a transformé la chimie des matériaux. Le problème de la détermination de structure est en grande partie non résolu, en particulier si le système étudié est situé à une surface et n'a pas de périodicité, comme dans la plupart des matériaux fonctionnels actuels. La Résonance Magnétique Nucléaire (RMN) à l’état solide serait une méthode de choix pour caractériser les surfaces mais la limite de détection de la RMN est beaucoup trop faible pour permettre à la RMN de caractériser les surfaces. L’introduction récente d’une nouvelle approche utilisant la Polarisation Dynamique Nucléaire (DNP) pour améliorer la sensibilité de la RMN des surfaces (DNP SENS) permet à présent de réaliser des expériences qui étaient totalement impossible il y a quelques années encore. Plus particulièrement, grâce à la méthode DNP SENS, les présents travaux de thèse aboutissent à la première structure tridimensionnelle d’un complexe organométallique supporté sur silice, avec une précision de 0,7 Å. De nombreux aspects de l’expérience DNP SENS ont été exploré. Le transport de de l’hyperpolarisation par diffusion de spin est primordial et un modèle numérique dans les matériaux mésoporeux a été développé. De plus, une nouvelle matrice aqueuse se basant sur des gels polyacrylamides a été mise au point et utilisée pour la caractérisation par RMN de nanoparticules permettant ainsi d’étendre les domaines d’application de DNP SENS. Enfin les premières expériences RMN DNP combinant hauts champs magnétiques et haute fréquence de rotation d’échantillon sont présentées. / The ability to understand the properties of chemical systems relies on their detailed description at the molecular level. Over the last century, several methods based on X-ray diffraction have allowed a structure-based understanding of many materials. However, several key questions often remain unanswered. In particular when the system under investigation is located on a surface. Although an extensive range of surface-sensitive methods are available for surface science and give valuable information, they only lead to a partial understanding of surfaces at the molecular level. Moreover, these methods are not compatible with all kinds of materials and usually require the use of a model and pristine surface. Solid-State NMR would be a method of choice to characterize surfaces. However, the approach suffers from its intrinsically low sensitivity and this is strongly emphasize in the case of surfaces where the atoms of interest are diluted in the matrix. Dynamic Nuclear Polarization (DNP) applied to surfaces (SENS) recently emerged as a very promising method to characterize surface sites. It offers a dramatic enhancement of NMR sensitivity and DNP applied to materials has led to many examples in the last ten years. In the present thesis, I have shown that DNP SENS, in combination with EXAFS, allowed the detailed 3D structure determination of the silica-supported organometallic complex determined with a precision of 0.7 angstroms. In parallel, some experimental aspect of DNP SENS have been explored. A spin diffusion has been developed to understand diffusion of hyperpolarization in porous media. A new aqueous DNP matrix, coined DNP Jelly, has been developed to characterize nanoparticles and thus expanding experimental range of DNP SENS. Finally, the first experiment of DNP NMR at fast magic angle spinning (up to 40 kHz) and high field are reported.

Le développement des systèmes multiprocesseurs intégrés sur puce (MPSoC) répond au besoin grandissant des architectures de calcul intensif. En revanche, l'évolution de leurs performances est entravée par leurs réseaux de communication sur puce (NoC) à cause de leur consommation d'énergie ainsi que du retard. C'est dans ce contexte que les NoC à base d'interconnexions RF et filaires (RFNoC) ont émergé. Afin de gérer au mieux et d'optimiser la conception d'un RFNoC, il est indispensable de développer une plateforme de simulation intégrant à la fois des circuits analogiques et numériques.Dans un premier temps, la simulation temporelle d'un RFNoC avec des composants dont les modèles sont idéaux est utilisée pour optimiser l'allocation des ressources spectrales disponibles. Le cas échéant, nous proposons des solutions pour améliorer la qualité de signal transmis. Dans un deuxième temps, nous avons développé en VHDL-AMS des modèles comportementaux et précis de chacun des composants du RFNoC. Les modèles de l'amplificateur faible bruit (LNA) et du mélangeur, prennent en compte les paramètres concernant, l'amplification, les non-linéarités, le bruit et la bande passante. Le modèle de l'oscillateur local considère les paramètresconventionnels, notamment le bruit de phase. Quant à la ligne de transmission, un modèle fréquentiel précis, incluant l'effet de peau est adapté pour les simulations temporelles. Ensuite, l'impact des paramètres des composants sur les performances du RFNoC est évalué afin d'anticiper les contraintes qui s'imposeront lors de la conception du RFNoC. / The development of multiprocessor systems integrated on chip (MPSoC) respondsto the growing need for intensive computation systems. However, the evolutionof their performances is hampered by their communication networks on chip(NoC) due to their energy consumption and delay. It is in this context that the wired RF network on chip (RFNoC) was emerged. In order to better manage and optimize the design of an RFNoC, it is necessary to develop a simulation platform adressing both analog and digital circuits.First, a time domaine simulation of an RFNoC with components whose modelsare ideal is used to optimize the allocation of the available spectrum resources. Where appropriate, we provide solutions to improve the quality of transmitted signal. Secondly, we have developed, in VHDL-AMS, behavioral and accurate models of all RFNoC components. The models of the low noise amplifier (LNA) and the mixer take into account the parameters for the amplification, nonlinearities, noise and bandwidth. The model of the local oscillator considers the conventional parameters, including its phase noise. Concerning the transmission line, an accurate frequency model, including the skin effect is adapted for time domaine simulations. Then, the impact of component parameters on RFNoC performances is evaluatedto anticipate constraints of the RFNoC design.

This thesis is focused on application samples with the inner insert used for Charpy impact test. This insert is welded to additional material by electron beam with pre-selected welded parameters. These parameters were chosen from data of performed experiments on homogenous welds. Resulting heterogenous weld was performed of evaluation of the microstructure, chemical composition and microhardness. Experimental materials were used austenitic steel 17 240 and ferritic steel 17 153 used on high-temperature applications.

The object of this thesis is to get a deeper understanding of the role of modulator agents in the synthesis of Zr- and Hf-based metal-organic frameworks (MOFs) and their impact on framework properties, such as textural properties, stability, hydrophobicity, and catalytic activity. For this purpose, MOFs are investigated that are built up by the commercially available linker 2,5-thiophenedicarboxylate and the Zr6(µ3-O)4(µ3-OH)412+ cluster. With proper choice of the modulator a new structure, namely DUT-126 (DUT = Dresden University of Technology), could be presented in the course of this work, besides the already known polymorphs of DUT-67, DUT-68 and DUT-69. Furthermore, DUT-67 is chosen as a model structure to functionalise the metal cluster of the framework by exchanging the modulator post-synthetically with hydrophobic fluorinated monocarboxylic acids. With the introduction of these fluorinated molecules, the surface polarities and the stability against water removal can be tuned. In addition, the metal clusters of DUT-67 were modified with a complete removal of the pristine modulator molecules by means of an acidic treatment in order to generate open metal sites that can function as Lewis acid sites. The suitability of DUT-67 and its acid treated analogues as heterogenous catalyst was tested on the Meerwein-Ponndorf-Verley reduction of cyclohexanone. Furthermore, the UiO-67 analogue DUT-122, which contains the luminescent linker 9-fluorenone-2,7-dicarboxylate, was tested as sensor material to detect solvent vapours. It could be shown that DUT-122 is sensitive to various solvent vapours, which induce photoluminescent shifts and intensity changes of the fluorescence emission profile depending on the polarity and the functionality of the respective solvent.