This compilation dissertation consists of four essays with the common theme of welfare analysis of long-term public investments. The first two essays focus on analysis of climate change mitigation, i.e., the social cost of carbon dioxide. The third essay focuses on cost-benefit analysis (CBA) of transport investment projects, while the last essay takes a broader perspective on welfare analysis. Essay 1: The Temporal Aspects of the Social Cost of Greenhouse Gases. The purpose of Essay 1 is to investigate the temporal aspects of the social cost of greenhouse gases. I find that the calculation period should ultimately be modeled to be consistent with the discount rate and that the “global-warming potential” concept is unsuitable for calculation of the social cost of GHGs other than carbon dioxide. Essay 2: Avoiding path dependence of distributional weights: Lessons from climate change economic assessments. In Essay 2, I explore shortcomings in income weighting in evaluation of climate change policy. In short, in previous versions of two of the most important existing models, regional economic growth is double counted. The proposed alternative approaches yield about 20–40% higher values of SCCO2 than the old approach. Essay 3: Does uncertainty make cost-benefit analyses pointless? In Essay 3, the aim is to investigate to what extent CBA improves the selection decision of projects when uncertainties are taken into account, using a simulation-based approach on real data of infrastructure investments. The results indicate that, in line with previous literature, CBA is a rather robust tool and considerably increases the quality of decision making compared with a random selection mechanism, even when high levels of uncertainty are considered. Essay 4: Household Production and the Elasticity of Marginal Utility of Consumption. In Essay 4, I develop a new model to show that omission of household production in a previous model leads to bias when the elasticity of marginal utility of consumption, EMUC, is estimated. I further offer new, unbiased estimates based on current evidence of the included parameters, suggesting a lower bound of EMUC at about 0.9.

[pt] Este trabalho consiste na determinação dos valores e da distrbuição dos módulos de elasticidade com a profundidade de maciços de solo estratificados através de retroanálises de provas de carga em estaca instrumentada, com medição de recalques no topo e na base, publicadas na literatura para depósito de solos resuduais, argila rija e areia. Nas retroanálises utilizou-se um programa computacional baseado numa versão simplificada do método dos elementos de contorno, sugerida por Poulos (1968), com adaptações da formulação de Mindlin (1936) para permitir também a consideração de maciços estratificados. Seus resultados foram comparados com aqueles obtidos por vários tipos de ensaios de campo ou de laboratório, com o objetivo de indicar quais destes ensaios são os mais adequados para a determinação dos parâmetros de deformação do solo, visando o cálculo do recalque de estacas. Os valores de módulo de elasticidade computados nas retroanálises compararam-se satisfatoriamente com aqueles determinados com base nos ensaios que, durante a execução, induzem pequenas deformações no solo, ocorrendo, por outro lado, uma significativa subestimativa destes valores quando determinados em ensaios envolvendo grandes deformações. Este comportamento permitiu então concluir que uma escolha adequada do nível de deformações associada ao tipo de ensaio é essencial para a determinação das características de compressibilidade do solo na engenharia de fundações. / [en] This work consists of the determination of values and distribution of the modulus of elasticity with depth in layered soils through backanalysis of instrumented pile load tests, published in literature for residual soils, stiff clay and sand. In the backanalysis was used a simplified version of the boundary element method, originally introduced by Poulos and Davis (1968), with adaptations of Mindlin´s formulation to allow for the consideration of layered soils. The results of the backanalysis were compared with those obtained through many ´in situ´ and laboratory tests, with the aim of indicating which of those tests are more suitable for the determination of the deformation parameters of the soil, to be used in the evaluation of pile settlement. The values of elasticity modulus computed in the backanalysis agreed well with those determined from the tests which transmit small strains to the soil during its execution. On the other hand, these values were subestimated when obtained from tests that involve high strains. This behavior permitted the conclusion that an appropriate choice of the strain level, associated to the type of the test, is essential to the determination of the compressibility characteristics of the soil in foundation engineering problems. / [es] Este trabajo aborda la determinación de los valores de los módulos de elasticidad con profundidad de macizos de suelo estratificados así como su distribución. Dicha determinación se efectua a través de retroanálisis de pruebas de carga en estaca instrumentada, que aparecen publicadas en la literatura para depósito de suelos residuales, arcilla dura y arena. En el retroanálisis se utilizó un programa computacional basado en una versión simplificada del método de los elementos de contorno, sugerida por Polos (1968), con adaptaciones de la formulación de Mindlin (1936) que permiten considerar macizos estratificados. Con el objetivo de indicar cuál de estos ensayos resulta más adecuado para la determinación de los parámetros de deformación del suelo y para el cálculo del recalque de estacas, se compararon sus resultados con los obtenidos por varios tipos de ensayos de campo o de laboratorio. Los valores de módulo de elasticidad computados en el retroanálisis se compararan satisfactoriamente con los determinados con base en los ensayos que, durante la ejecución, inducen pequenas deformaciones en el suelo, teniendo, por otro lado, una significativa subestimación de estos valores cuando son determinados en ensayos con grandes deformaciones. Este comportamiento permitió entonces concluir que una selección adecuada del nível de deformación asociada al tipo de ensayo es esencial para la determinación de las características de compresibilidad del suelo en la ingeniería de fundaciones.

Magister Economicae - MEcon / Despite its recent remarkable economic growth, Ethiopia remains one of the poorest countries in the world. More than 80 percent of Ethiopians obtain their livelihood from traditional low-productivity agricultural activities. Due to lack of water storage facilities and the erratic nature of rainfalls, most farmers don’t have access to water to produce more than one crop per year and hence there are frequent crop failures due to droughts which have made the country one of the highest food insecure nations and receiver of food aid. It is evident that a comprehensive effort is required to increase crop and agricultural production through different intensification and productivity enhancement mechanisms and reduce rural household’s food insecurity and poverty. In line with this the Government of Ethiopia and different NGO’s have been promoting irrigation technology as a viable option in enhancing farm productivity and efficiency improvements.By integrating field observations, economic theory, and econometric analysis, this study assess the extent to which access to irrigation technology affects the level of technical efficiency in Gorogutu district of Eastern Ethiopia. The analysis is based on primary household-level data collected from 100 randomly selected households in 20010/11 cropping season. To analyze the effect of the technology on technical efficiency, three different Cobb-Douglas type of Stochastic Production Functions were estimated. More so, to explore different socio- economic and institutional determinants of technical efficiency in the study district, an inefficiency effect model was estimated using the one step procedure.The result from the estimated models has shown that farm households in the study area are not technically efficient and there is a chance to increase output by using the technology and mix of production input used by the best farm household (with 20 percent technical inefficiency). In addition, it also showed that households with access to irrigation technology are more technically efficient (84 percent technical efficiency) than those without access to the technology (77 percent technical efficiency). And household’s access to irrigation technology, access to extension service and distance travelled from farm plot to homestead are a significant determinant of technical efficiency in the study area.The study recommended, among other things, as a country that has a huge potential for irrigation development, utilization of this potential and providing irrigation technology to farm households will have a huge impact on the livelihoods of the majority of the poor. Evidently, efforts tailored towards this end would be very essential in militating against the high levels of poverty that is persistent in the communities

1 Abstract To study the effect a change in a tax base has on the corresponding tax revenue is a useful tool to better predict future tax revenues. This property is called a tax revenue elasticity but generally it does not get as much attention as it deserves, and when it does, key points like using data adjusted for the effects of tax reforms or distinguishing between the short-run (instantaneous) and the long-run (equilibrium) elasticity are often omitted. In my thesis, I am the first one to estimate the tax revenue elasticities for Slovakia. I use a unique dataset adjusted for the effects of tax reforms and tax changes to estimate both the short-run and the long-run elasticities for the three tax categories th at account for the majority of each year's tax revenue - Personal Income Tax, Corporate Income Tax and Value Added Tax. I obtain a long-run elasticity of 0.98, 1.28 and 0.94 for the Personal Income Tax, the Corporate Income Tax and the Value Added Tax respectively and a short-run elasticity of 3.51 and 1.93 for the Corporate Income Tax and the Value Added Tax respectively. I do not obtain a significant estimate in the case of the Personal Income Tax. Additionally, I find that it takes more than a year for the elasticity to reach its equilibrium value for all the three tax categories and that there...

Dans cette thèse, on s'intéresse au comportement effectif non linéaire issu de l'homogénéisation d'un milieu désordonné de fibres dans le plan. A partir d'une hypothèse de déformation homogène, on obtient une loi de comportement non linéaire isotrope par intégration sur les orientations de fibres. La particularité du modèle réside dans la représentation du flambement des fibres par une loi de comportement de type ressort avec raideurs asymétriques en traction/compression. Dans un premier temps, la limite d'une raideur nulle en compression est étudiée numériquement par éléments finis sur des géométries planes fissurées. On montre que le champ de contrainte solution est constitué d'un ensemble de graphe de force de traction en équilibre avec le chargement. En particulier, le caractère unilatéral révèle une interaction forte des fissures : la raideur en traction d'une éprouvette fissuré peut-être nulle quand bien même la percolation des fissures n'est pas atteinte. Par ailleurs, on montre que le champ de contrainte est partitionné en régions auto-équilibrées et libres de contrainte Pour finir, on propose une application au calcul des bornes énergétiques de la solution élastique d'un problème aux limites. En perspective, on met en évidence le caractère bi-module d'un voile de fibres de verre avec des mesures de champs de déplacement par corrélations d'images. Un dispositif d'Arcan est mis en place pour exercer un chargement anisotrope sur le voile. Les champs de déplacement mesurés sont utilisés pour identifier une loi de comportement du matériau. Un résultats préliminaire montre que le caractère unilatéral du voile est d'autant plus prononcé que sa densité est faible. / An homogenized non linear mechanical behavior of a 2D disordered fiber mats is considered. Under the homogeneous strain assumptions, a continuum description of an isotropic non linear media is derived by integration over all fibers orientations. The fiber non linearity due to buckling is featured by a lower spring constant in compression than in traction. First, the response of a sheet containing multiple cracks with different geometries is explored numerically in the case of a tension-field material, corresponding to the singular limit where the compressive spring constants goes to zero. It is reported that the stress solution is composed of a set of pattern built from tensile branches in equilibrium with the boundary conditions. In particular, the unilateral feature reveal a strong interaction between multiple cracks : the tensile stiffness of a cracked sheet can be zero even though the sheet is made up of a single piece. Besides the pattern of tensile branches, it is reported a partitioning of the stress into self-equilibrated and stress free regions. Finally, an application is proposed to find good estimates of the energetic bounds of the boundary value problem. As an experimental perspective to this work, it is proposed to estimates the bi-modulus feature of a manufactured fiber glass veil using digital image correlations. An Arcan device is set up to enforce an anisotropic loading on the veil. Measured displacement fields are used to identify a material constitutive law. As a preliminary results, it is reported that the unilateral feature is noticeable in light weight fiber glass veil.

No description available.

Omnipresence of heterogeneity is conspicuous in all creations of nature. Heterogeneity manifests itself in many forms at different scales, both in time and space. Engineering domain being an exotic fusion of human creativity and ever-increasing demands exemplifies the ubiquity of heterogeneity. Surprisingly, the plethora of materials we see around seem to stem from myriad combination of few base materials identified as elements in chemistry. Further, a simple rearrangement of atoms in these materials leads to allotropes with startling contrasts in properties. Similarly, micro- and meso-scales in heterogeneous materials also dis-play this phenomenon. Human requirements propelled by necessities and wants have leveraged heterogeneity deliberately or naively. In the context of engineering materials, light weight heterogeneous materials like composites and cellular solids are outstanding inventions from the last century. The present thesis highlights this phenomenon on a meso-scale to explore generalized variants of circular and elliptical honeycomb structures (HCSs) with an emphasis on their effective transverse elastic responses, a crucial pillar of engineering design and analysis. Homogenized or effective properties are an extension of continuum hypothesis, conceived for ease in analyses. E ective properties are employed in multi-scale analyses resulting in less complex models for analysis, for example, for predicting the speed of wave propogation. The thesis extends and generalizes existing close-packed circular and elliptical HCSs to more broader configurations. Simpler periodic arrangement of the unit cells from numerous exotic possibilities directly incorporates Design for Manufacture and Assembly (DFMA) philosophy and o ers a potential scope for analysis by simpler tools resulting in handy expressions which are of great utility for designer engineers. In this regard, analytical expressions for moduli having compact forms in the case of circular HCS are developed by technical theories and rigorous theory of elasticity. Regression analysis expressions for the moduli of elliptical HCS are presented, and the elasticity solutions for the same are highlighted. The thesis consists of seven chapters with Chapter 1 presenting generalized circular and elliptical HCSs as a potential avenue beyond composite materials. Following a survey of pertinent HCS literature of these HCSs, research gaps and scope are delineated. Chapter 2 briefly y summarizes the ideas, concepts and tools including analytical and numerical methods. This chapter sets the ground for the analysis of generalized circular and elliptical HCS in the following four chapters. Following the classification of the circular HCSs, Chapter 3 assesses the complete transverse elastic responses of generalized circular HCS through technical theories which are a first-order approximation. Here, thin ring theory and the more elaborate curved beam theory are employed as models to assess the moduli. Normal moduli - E and - are obtained by employing Castigliano method, while shear moduli (G ) are obtained by solving the differential equations derived in terms of displacements. Compact expressions for moduli presented wherever possible furnish the designer with a range of moduli for different configurations and modular ratios (Ey=Ex). The results show the range of applicability of technical theories within 5% of FEA. For hexagonal arrays, these results are more refined than those in literature; while the same are new for other configurations. Surprisingly, the more elaborate curved beam theory offers no better results than the thin ring theory. Chapter 4 extends the aforementioned task of assessing the complete trans-verse elastic moduli of generalized circular HCS by employing rigorous theory of elasticity (TOE) which is a second-order approximation. Utilizing Airy stress function in polar coordinates, the boundary value problems resulting from modeling of the circular HCS under different loads are solved analytically in conjunction with FEA employing contact elements. Contact elements circumvent the point loads which give finite values of displacements in technical theories and singular values in TOE. A widely used idea of employing distributed load, statically equivalent to point load, is invoked to empower TOE. The distributed load is assumed a priori and the contact length is obtained from FEA employing con-tact elements. Thus, FEA compliments the present analytical methods. Results demonstrate a very good match between analytical method in conjunction with FEA and numerical results from FEA; the error is within 5% for very thick ring (thickness-radius ratio 0.5). Further, computationally and numerically efficient expressions for displacements give better results with same computational facility. To illustrate the effect of coating on effective moduli, a limited study based on thin ring theory and elasticity theories is undertaken in Chapter 4. The study explores the effects of moduli and thickness ratios of substrate to coating on the effective normal moduli. Employing thin ring theory with only flexure as the bending mode, we get compact expressions giving good match for very thin rings in all confifigurations. The elasticity approach presented for square array demonstrates a very good match with FEA for thick rings. Coatings offer a strategy to increase the effective moduli with same dimensions. Chapter 5 broadens the scope of circular HCS by considering elliptical HCSs. While generalized circular HCS can cater to anisotropic requirement to an extent, larger spectrum is offered by considering elliptical honeycomb structures. In this regard, a generalized version of concentric thin coated elliptical HCS is investigated for transverse moduli. Thin HCSs are explored by technical theories as in circular HCS. However, a lack of exact compact-form expressions necessitates the use of regression analysis. The resulting expressions are presented in terms of ellipticity ratio describing the ovality of the ellipse and geometric parameters. Normal moduli are obtained by Castigliano method implemented in MATHE-MATICA, but shear moduli are obtained from FEA employing beam elements. The need for FEA employing beam elements stems from the subtle fact that Castigliano method implicitly assumes preclusion of rigid body motions, while shear loading for shear moduli evaluation entails rigid body motions. Interestingly, curved beam theory, as in circular HCS, offers no better refinement in assessing the moduli as compared to thin ring theory. The graphs showing the moduli with respect to thickness and modular ratios are presented as design maps to aid the designer. Chapter 6 extends the works of thin concentric coated elliptical to thicker concentric and a novel confocal elliptical HCS, a variant of elliptical HCS. In this regard, thick concentric and confocal elliptical HCS by elasticity approach are attempted for a simple case. Airy stress function in polar coordinates is tried for concentric elliptical HCS. Confocal HCS analysis employs stress function in terms of elliptical coordinate system. After proving the correctness of the stress function for both the cases by comparing the reconstructed boundary conditions with actual boundary conditions, the restrictions in solving the case of rings under load over a small region is highlighted. A parametric study for moduli is under-taken by employing FEA. These are presented as design graphs which compare and contrast the two variants of elliptical HCS on the same graphs. The modular ratio (Ey=Ex) is conspicuously more for confocal elliptical HCS than concentric elliptical HCS. Chapter 7 gives the conclusions in a nutshell, and explores the feasibility of stress evaluation of heterogeneous media on the lines of effective media theory.

Proteins are essential parts of living organisms that initiate and control almost all cellular processes. Despite the widely accepted belief that all functional proteins fold into stable and well-defined three-dimensional (3D) structures mandatory for protein activity, the existence of biologically functional disordered proteins has been increasingly recognized during past two decades. Proteins with inherent structural disorder, commonly known as intrinsically disordered proteins (IDPs), play many roles in a biological context. However, in contrast to their folded counterparts, they are dynamically unstructured and typically fluctuate among many conformations even while performing biological functions. In fact, it is this dynamical structural heterogeneity that that allows for IDPs to interact with other biological macromolecules in unique ways. Moreover, while a majority of proteins in eukaryotic proteomes have been found to have intrinsically disordered regions (IDR), the mechanisms by which protein disorder fives rise to biological functionality is still not well understood. Through a series of simulation studies on specific systems, this thesis probes several aspects of the emerging structure-function paradygm of IDPs, namely the mechanics, intermolecular assembly, and structural transitions occurring in these proteins. The lack of well-defined 3D structure in IDPs gives rise to distinct mechanical properties, the subject of the first study in the thesis on the elasticity of a elastomeric gluten-mimetic polypeptide with an intrinsically disordered character. This disordered polypeptide was shown to exhibit distinctively variable elastic response to a wide range of tensions, which a classical worm-like chain model failed to accurately describe, thus requiring a molecular-level analysis. IDPs frequently are frequently involved in protein-protein interactions, the focus of the second study on the propensity of an IDR, the B domain in dynamin-related protein 1 (Dpr1), to self-assemble into dimer structures while remaining disordered in all solution conditions. Despite a hypothesized auto-inhibitory role for this domain in Dpr1 that was assumed to be triggered by an disordered-to-order transition, the B domains in solution showed no tendency to form ordered structures even in the presence of order promoting osmolytes. Instead, self-association in the presence of osmolyte was found to occur by favorable intermolecular intereactions between specific region on the surface of the B-domains. Other IDPs do undergo a disorder-to-order transition in response to environmental cues, in ways that are unique disordered proteins, the focus of the last study on intermolecular ordering transitions in silk-like proteins. Factors such as protein sequence and physical tension were investigated, and results suggested that tyrosine residues in the key silk sequence motifs promote templating of beta structure from disordered precursors and that elongational stresses preferentialy stabilize antiparallel beta-sheet order. Together, these three computational studies provide insight into the nature of the structure-function mechanisms of IDPs.

Plusieurs lois de comportement mécaniques possèdent une formulation tensorielle, comme c'est le cas pour l'élasticité où intervient un espace de tenseurs d'ordre 4, noté Ela. La classification des matériaux élastiques passent par la nécessité de décrire l'espace des orbites ELA/SO(3). Plus généralement, on étudie la géométrie d'un espace de tenseurs sur $mathbb{R}^{3}$, via l'action du groupe O(3). Cette géométrie est caractérisée par ses classes d'isotropies, ou encore classes de symétries. Tout espace de tenseurs possède en effet un nombre fini de classes d'isotropies. Nous proposons alors une méthode originale et générale pour obtenir ces classes d'istropie. Nous avons ainsi pu obtenir pour la première fois les classes d'isotropie d'un espace de tenseurs d'ordre 8 intervenant en théorie de l'élasticité linéaire du second-gradient de la déformation.Pour une représentation réelle d'un groupe compact, l'algèbre des polynômes invariants sépare les orbites, d'où la recherche d'une famille génératrice minimale de cette algèbre. Pour cela, on exploitant le lien entre les espaces de tenseurs et les espaces de formes binaires. Nous avons ainsi repris et ré-interprété les approches effectives de cette théorie, développées par Gordan au 19ième siècle. Cette ré-interprétation nous a permis d'obtenir de nombreux résultats, dont une famille génératrice minimale d'invariants pour l'élasticité mais aussi pour la piézoélectricté. Nous avons pu retrouver d'une façon simple les séries de Gordan, ainsi que des relations plus récentes d'Abdesselam--Chipalkatti sur les transvectants de formes binaires. / Tensorial formulation of mechanical constitutive equations is a very important matter in continuum mechanics. For instance, the space of elastic tensors is a subspace of 4th order tensors with a natural SO(3) group action. More generaly, we have to study the geometry of a tensor space defined on $mathbb{R}^{3}$, under O(3) group action.To describe such a geometry, we first have to exhibit its isotropy classes, also named symetry classes. Indeed, each tensor space possesses a finite number of isotropy classes. In this present work, we propose an original method to obtain isotropy classes of a given tensor space. As an illustration of this new method, we get for the first time the isotropy classes of a 8th order tensor space occuring in second strain-gradient elasticity theory. In the case of a real representation of a compact group, invariant algebra seperates the orbits. This observation motivates the purpose to find a finite generating set of polynomial invariants. For that purpose, we make use of the link between tensor spaces and spaces of binary forms, which belongs to the classical invariant theory. We thus have to deal with SL(2,$mathbb{C}$) group action. To obtain new results, we have reformulated and reinterpreted effective approaches of Gordan's algorithm, developped during XIXth century. We then obtain for the first time a minimal generating family of elasticity tensor space, and a generating family of piezoelectricity tensor space. Using linear algebra arguments, we were also able to get important relations of classical invariant theory, such as the Gordan's series and the Abdesselam--Chipalkatti's quadratic relations on transvectants.

D’un point de vue mécanique, la peau est une structure multicouche complexeayant des propriétés viscoélastique, non-linéaire, quasi-incompressible, anisotrope eten état de précontrainte. Le travail présenté dans cette thèse associe expérimentation,modélisation et identification numérique et se distingue en particulier parl’utilisation d’un dispositif d’extensométrie développé au laboratoire et adapté à desmesures in vivo non invasives. Des tests ex vivo ont cependant été réalisés égalementà titre de comparaison et de validation. Une attention particulière a été portée à latension cutanée initiale (ou naturelle). Les essais in vivo ont permis d’obtenir desréponses force – déplacement sous différentes configurations angulaires, d’intensitéet pour diverses localisations corporelles. Les essais ex vivo ont quant à eux permisd’estimer l’état de contrainte initiale par la mesure des forces nécessaires à la remiseen tension d’explants. Ces différents essais expérimentaux ont été modélisés en utilisantdeux lois de comportement : la loi d’Ogden du premier ordre permettant dedécrire un comportement hyperélastique isotrope et la loi d’Holzapfel-Gasser-Ogden(HGO) décrivant un comportement hyper élastique anisotrope. Cette dernière a étéimplémentée sous l’interface utilisateur du logiciel ANSYS. Les paramètres caractéristiquesdes zones cutanées testées ont été identifiés par méthode inverse. L’influencede la compressibilité de la peau sur son comportement mécanique est mise en évidence.Au final, les travaux de cette thèse ont été appliqués au lambeau d’avancementde type V-Y qui est une technique de suture pratiquée pour combler les pertes desubstance.229 / From a mechanical point of view, the human skin is a complex multilayerstructure with viscoelastic, non-linear and anisotropic properties and a pre-stressstate. The work presented in this thesis combines experimentation, modeling andnumerical identification and distinguishes especially by the use of an extensometerdevice developed in the laboratory and suitable for non-invasive in vivo measurements.Ex vivo tests were however also performed for comparison and validation.Particular attention was paid to the initial skin tension. in vivo tests allowed theobtaining of load – displacement responses for different angular configurations, intensitiesand body locations. ex vivo tests in turn allowed the estimation of the stateof initial stress by measuring the forces necessary for the re-tension of the explants.These different experimental tests were modeled using two constitutive laws : thefirst order Ogden law allowing the description of an isotropic hyperelastic behavior,and the Holzapfel-Gasser-Ogden’ law (HGO) allowing the description of an anisotropichyperelastic behavior. The latter was implemented in the user interface ofANSYS software. The characteristics parameters of the skin areas tested were identifiedby the reverse method. The influence of the compressibility of the skin on itsmechanical behavior is highlighted. Finally, the work of this thesis were applied toan advancement flap of V-Y type.