This dissertation consists of three essays, taking different perspectives on human capital. The first essay looks at human capital from a growth perspective. Essays two and three focuses on the individual’s occupational decision and its relation to family background. The first essay attempts to capture the effects on long run economic growth and transitional dynamics of the interaction between human capital and R&amp;D. We do this by allowing for endogenous human capital accumulation in an economy where the number of products and technologies expands because profit maximizing entrepreneurs do R&amp;D. We find that, in the absence of scale effects, long run growth is determined by the economy’s capacity to accumulate human capital. A relative lack of R&amp;D capital causes the economy to grow slowly during its transition to the steady state, while a relative abundance of R&amp;D capital gives high growth rates during transition. In the second essay, the classical Roy-model of selection on the labor market is extended in order to analyze intergenerational mobility. This is done through the introduction of ability uncertainty that is linked to family background. In contrast to to additional human capital models of intergenerational mobility, this mechanism rather than differences in access to capital markets links occupational oucomes of offspring to parents. We study the effects of income redistribution on mobility and talent allocation. It is found that redistribution has implications for intergenerational mobility and talent allocation through its influence on individual occupational choices. However, we conclude that the presence of a trade-off between redistribution and intergenerational mobility depends on the extent of similarity of occupations with regard to ability sensitivity and wage rates, and on the degree of individual risk aversion. Whether redistribution occurs only within an occupation or simultaneously within and across occupations is also inportant for the implicatons for mobility and talent allocation. In essay three, a model of occupational choice and human capital investment is developmed and tested. The model allows family background to influence occupational choice through access to economic resources, differences in costs of schooling, and ability uncertainty linked to background similar to that discussed in essay two. It is predicted that life time utility of children from less well-off background is more sensitive to economic incentives when risk aversion is strong. The model also predicts that people are more sensitive to economic incentives when considering occupations distant from their parent occuations. The implications of the theoretical model are tested and largely confirmed on Swedish data using a mixed multinominal logit framework which explicitly accounts for unobserved ability heterogeneity. / <p>Diss. Stockholm : Handelshögskolan, 1998</p>

There is an excessive demand for the rehabilitation of frame type reinforced concrete (RC) buildings which do not satisfy current earthquake code provisions. Therefore, it is imperative to develop user-friendly seismic strengthening methodologies which do not necessitate the evacuation of building during rehabilitation period. In this study, it was aimed to strengthen the brick infill walls by means of diagonal Carbon Fiber-Reinforced Polymer (CFRP) fabrics and to integrate them with the existing structural frame in order to form a new lateral load resisting system. The possible effects of height to width (aspect) ratio of the infill walls and scale of the frame test specimens on the overall behavior attained by the developed rehabilitation methodology were investigated. The experimental part of the study was carried out in two steps. In the first step, ten individual panel specimens were tested in order to understand the behavior of strengthened/non-strengthened masonry walls under diagonal earthquake loads. And in the second step, the tests of eight 1/3 and four 1/2 scaled one-bay, two-story RC frames having two different aspect ratios were performed to determine design details. The experimental results were revealed in terms of lateral stiffness, strength, drift and energy dissipation characteristics of the specimens. In the analytical part, an equivalent strut and tie approach was used for modeling the strengthened/non-strengthened infill walls of the frames. The predicted pushover responses of the frame models were compared with the test results. The design criteria required for the aforementioned strengthening methodology was developed referring these analytical results.

Nous analysons les propriétés dynamiques de milieux architecturés périodiques et de réseaux fibreux aléatoires en petites et grandes déformations, à partie de méthodes d’homogénéisation afin de calculer leurs propriétés statiques et dynamiques. Des modèles effectifs de type micropolaire et du second gradient sont élaborés afin de prendre en compte l’impact de la microstructure sur le comportement effectif. L’influence des degrés de liberté en rotation additionnels et des gradients d’ordre supérieur du déplacement sur les relations de dispersion sont analysés pour des comportements élastique et viscoélastique du matériau constitutif. Les milieux continus généralisés ainsi construits conduisent à des effets dispersifs, en accord avec les observations. Dans la seconde partie du travail, nous analysons l’influence des grandes déformations sur la propagation des ondes élastiques dans des milieux architecturés périodiques. Des méthodes théoriques assortis de schémas numériques sont développés afin de prédire l’influence des déformations finies générées au sein des structures sur l’évolution de leur diagramme de bande. Un schéma incrémental d’évolution de la fréquence et de la vitesse de phase du milieu continu homogénéisé est établi, à partir d’une méthode de perturbation établie pour des structures 1D, 2D et 3D, en considérant plus particulièrement des structures auxétiques. Ce schéma montre un effet important de l’état de déformation appliquée et de la densité effective sur l’évolution de la fréquence et de la vitesse de phase des ondes. Une méthode de perturbation spécifique aux structures périodiques nonlinéaires est développée afin de généraliser le théorème de Bloch pour couvrir les non linéarités tant géométriques que matérielles. Des modèles hyperélastiques du premier et du second gradient de différentes structures sont identifiés par des tests virtuels reposant sur une méthode d’homogénéisation dédiée, qui permettent de formuler des équations d’onde spécifiques – équations de Burgers et de Boussinesq – dont les propriétés dispersives sont analysées / Micropolar and second gradient effective continua are constructed as two different strategies to account for microstructural effects. The influence of additional degrees of freedom or higher order displacement gradients on the dispersion relations is analyzed in both situations of elastic and viscoelastic behaviors of the material. Generalized effective continua lead to dispersive waves, as observed in experiments. In the second part of the thesis, we analyze the influence of large deformations on the propagation of acoustic waves in repetitive network materials. Both theoretical and numerical methods are developed in order to assess the influence of finite strains developing within the networks on the evolution of their band diagrams. An incremental scheme for the update of frequency and phase velocity of the computed homogenized medium is developed based on a perturbation method for 1D, 2D and 3D structures, considering with a special emphasis auxetic networks. This scheme shows an important effect of the applied finite deformation on the frequency and phase velocity of the propagating waves. A perturbation method for nonlinear periodic structures is developed to extend Bloch’s theorem to cover both geometrical and material nonlinearities. Hyperelastic first and second order gradient constitutive models of different network materials are identified based on dedicated homogenization methods, from which specific wave equations are formulated - Burgers and Boussinesq equations - the dispersion properties of which are analyzed

Chute aerators are widely used in spillways to avoid cavitation damage. When the water flow passes the aerator, two jets form – upper and lower jet. The purpose of this thesis has been to study the effects from the aerator by conducting experiments in a model with a flow depth large enough to ensure that the upper and lower jet remain separated. This means that the effects from the self-aeration at the upper surface has no effect on the process in the lower jet, thus making it possible to quantify the effects from the aerator. This thesis has also provided information of the bubble formation in the lower jet to aid in the ongoing research at Sichuan University. The following questions were set up for this thesis: • What is cavitation and how is it harmful? • What is the working principle of an aerator? • How is air concentration and bubble frequency distributed in the flow? • How well do the experimental results coincide with theoretical calculations? • How are air bubbles formed and transported within the flow? The effects from the aerator have been quantified by measuring the air concentration and bubble frequency throughout the cavity zone. The model was modified and the velocity was varied between the experiments to study how different parameters effected the aeration. The results indicate that much air is being entrapped in the lower surface, but only a small amount of the entrapped air is being entrained into the flow and that the bubble frequency increases with both distance from the aerator and with an increased flow velocity. No difference in behaviour was noticed between the different modifications of the model. The bubble formation was studied by recording the flow with a high-speed camera. These recordings were used to obtain data about important parameters for the ongoing research at Sichuan University.

This dissertation presents an investigation of the effects of stress, and of absolute and relative particle size, in tests on vertically loaded footings. Two granular materials, namely, a silica rock flour and a Chatelet flint grit, which differed in nominal diameter by a factor of 50 but were otherwise practically similar in all other grain characteristics were used in this work. A comprehensive series of triaxial tests under a wide range of cell pressures was carried out to quantify the stress and absolute particle size effects. Model footing tests were also performed by pushing a rigid circular punch axisymmetrically into the flat surface of a cylindrical soil model either under 1-g (gravity) with surcharge or under elevated g in a centrifuge. The 1-g and centrifuge test series were used to study the scale effects on the surcharge term Ng and the self-weight term Nγ of the Terzaghi bearing capacity equation, respectively. Parameters varied were punch diameter, particle size and surcharge or g level. Two theoretical analyses were attempted based on the finite element method and the method of characteristics. Using the Schofield Soil Model, the finite element analysis can give a reasonable order of magnitude prediction for the settlement of the footing under working load conditions. When the effect of reducing angle of shearing with increasing stress was taken into account together with the change of geometry due to footing penetration, the angles of shearing inferred from the method of characteristics fall within ±20 of those measured in triaxial compression tests. Distortion due to violating the scaling law by not conserving the ratio of particle size to model dimension was not considered to be significant. Distortion due to violating the constitutive soil behaviour by varying the absolute particle size was found to be significant due to differences in grain crushing, but this can be accounted for effectively by the new style of calculations developed in the thesis.

Ageing of low alloy steel in nuclear applications commonly takes the form as a hardening and an embrittlement of the material. This is due to the evolution of the microstructure during irradiation and at purely thermal conditions, as a combination or separate. Irradiation introduces evenly distributed solute clusters, while thermal ageing has been shown to yield a more inhomogeneous distribution. These clusters affect the dislocation motion within the material and results in a hardening and in more severe cases of ageing, also a decreased work hardening slope due to plastic strain localization into bands/channels. Embrittlement corresponds to decreased fracture toughness due to microstructural changes resulting from ageing. The thesis presents a possible framework for modeling of ageing effects in low alloy steels.In Paper I, a strain gradient plasticity framework is applied in order to capture length scale effects. The constitutive length scale is assumed to be related to the dislocation mean free path and the changes this undergoes during plastic deformation. Several evolution laws for the length scale were developed and implemented in a FEM-code considering 2D plane strain. This was used to solve a test problem of pure bending in order to investigate the effects of the length scale evolution. As all length scale evolution laws considered in this study results in a decreasing length scale; this leads to a loss of non-locality which causes an overall softening at cases where the strain gradient is dominating the solution. The results are in tentative agreement with phenomena of strain localization that is occurring in highly irradiated materials.In Paper II, the scalar stress measure for cleavage fracture is developed and generalized, here called the effective normal stress measure. This is used in a non-local weakest link model which is applied to two datasets from the literature in order to study the effects of the effective normal stress measure, as well as new experiments considering four-point bending of specimens containing a semi-elliptical surface crack. The model is shown to reproduce the failure probability of all considered datasets, i.e. well capable of transferring toughness information between different geometries. / Åldring av låglegerade stål i kärntekniska användningsområden framträder typiskt som ett hårdnande och en försprödning av materialet. Detta på grund av utvecklingen av mikrostrukturen under bestrålning och under rent termiska förhållanden. Bestrålning introducerar jämt fördelade kluster av legeringsämnen. Termisk åldring har däremot visats ge upphov till en mer ojämn fördelning. Klustren hämmar dislokationsrörelsen i materialet och ger därigenom upphov till en ökning av materialets sträckgräns, vid en mer påtaglig åldring det även leda till ett sänkt arbetshårdnande på grund av lokalisering av plastisk töjning i s.k. kanaler/band. Försprödning är en sänkning av materialets brottseghet som en följd av de mikrostrukturella förändringar som sker vid åldring. Arbetet som presenteras i den här avhandlingen har gjorts i syfte till att ta fram ett möjligt ramverk för modellering av låglegerade stål.I Artikel I, används en töjningsgradientbaserad plasticitetsteori för att kunna fånga längdskalebeteenden. Längdskalan i teorin antas vara relaterad till dislokationernas medelfria väg och den förändring den genomgår vid plastisk deformation. Flera utvecklingslagar för längdskalan har analyserats och implementerats i en finita element kod för 2D plan deformation. Denna implementering har använts för att lösa ett testproblem bestående av ren böjning med syfte att undersöka effekterna av utvecklingen hos längdskalan. Alla de utvecklingslagar som presenteras i artikeln ger en minskande längdskala, vilket leder till vad som valt att kallas förlust av icke-lokalitet. Fenomenet leder till ett övergripande mjuknande vid fall där den plastiska töjningsgradienten har stor inverkan på lösningen. Resultaten är i preliminär överenstämmelse med de typer av lokalisering av plastisk töjning som observerats i starkt bestrålade material.I Artikel II utvecklas ett generaliserat spänningsmått i syfte att beskriva klyvbrott, här benämnt effektivt normalspänningsmått. Detta har använts i samband med en icke-lokal svagaste länk modell, som har applicerats på två experimentella studier från den öppna litteraturen i syfte att studera effekterna av det effektiva normalspänningsmåttet. Utöver detta presenteras även nya experiment på ytspruckna provstavar under fyrpunktsböj. I artikeln visas att modellen återskapar sannolikheten för brott för alla undersökta experimentuppställningar, d.v.s. modellen visas vara väl duglig för att överföra brottseghet mellan geometrier. / <p>QC 20190312</p>

This thesis presents three papers within the field of dynamic macroeconomics. The first paper, entitled “Medium-frequency cycles and the remarkable near trend-stationarity of output”, presents a dynamic stochastic general equilibrium model with endogenous growth, capable of reconciling the observed large medium-frequency fluctuations in output, with its long run (near) trend-stationarity. This requires a model in which standard business cycle shocks lead to highly persistent movements around trend, without significantly altering the trend itself. The robustness of the trend also requires that scale effects are eliminated both in the long and short runs. In an estimated version of the model, a financial-type shock to the stock of ideas emerges as the key driver of the medium frequency cycle. The second paper, entitled “Learning from learners”, is an intervention into two long running debates: the first, on whether learnability may be used to rule out explosive paths for inflation in New Keynesian models, and the second, into whether Taylor rule parameters may be identified from observing the data. We find that in an economy populated with traditional macroeconomic learners, Taylor rule parameters can always be identified by sophisticated econometric techniques. Furthermore, when all agents in the economy use such sophisticated techniques, stationary sunspot solutions are readily learnable, and there is no guarantee of convergence to a stationary solution even in the “determinate” case. This implies that learnability cannot be used for equilibrium selection. Finally, in the third paper, “Efficient simulation of DSGE models with inequality constraints” (joint with Michael Paetz), we present a new algorithm for the simulation of models subject to inequality constraints, such as the zero lower bound on nominal interest rates. Our algorithm is shown to deliver higher accuracy than all other non-global algorithms, and leading speed. We go on to provide a number of applications of our algorithm.

In this thesis, the focus has been on micro-mechanical mechanisms in polymer-based materials and structures. The first part of the thesis treats length-scale effects on polymer materials. Experiments have showed that the smaller the specimen, the stronger is the material. The length-scale effect was examined experimentally in two different polymers materials, polystyrene and epoxy. First micro-indentations to various depths were made on polystyrene. The experiments showed that length-scale effects in inelastic deformations exist in polystyrene. It was also possible to show a connection between the experimental findings and the molecular length. The second experimental study was performed on glass-sphere filled epoxy, where the damage development for tensile loading was investigated. It could be showed that the debond stresses increased with decreasing sphere diameter. The debonding grew along the interface and eventually these cracks kinked out into the matrix. It was found that the length to diameter ratio of the matrix cracks increased with increasing diameter. The experimental findings may be explained by a length-scale effect in the yield process which depends on the strain gradients. The second part of the thesis treats mechano-sorptive creep in paper, i.e. the acceleration of creep by moisture content changes. Paper can be seen as a polymer based composite that consists of a network of wood fibres, which in its turn are natural polymer composites. A simplified network model for mechano-sorptive creep has been developed. It is assumed that the anisotropic hygroexpansion of the fibres leads to large stresses at the fibre-fibre bonds when the moisture content changes. The resulting stress state will accelerate creep if the fibre material obeys a constitutive law that is non-linear in stress. Fibre kinks are included in order to capture experimental observations of larger mechano-sorptive creep effects in compression than in tension. Furthermore, moisture dependent material parameters and anisotropy are taken into account. Theoretical predictions based on the developed model are compared to experimental results for anisotropic paper both under tensile and compressive loading at varying moisture content. The important features in the experiments are captured by the model. Different kinds of drying conditions have also been examined. / QC 20100910

All future Extremely Large Telescopes (ELTs) will be segmented. However, as their size grows, they become increasingly sensitive to external disturbances, such as gravity, wind and temperature gradients and to internal vibration sources. Maintaining their optical quality will rely more and more on active control means. This thesis studies active optics of segmented primary mirrors, which aims at stabilizing the shape and ensuring the continuity of the surface formed by the segments in the face of external disturbances.<p><p>The modelling and the control strategy for active optics of segmented mirrors are examined. The model has a moderate size due to the separation of the quasi-static behavior of the mirror (primary response) from the dynamic response (secondary, or residual response). The control strategy considers explicitly the primary response of the telescope through a singular value controller. The control-structure interaction is addressed with the general robustness theory of multivariable feedback systems, where the secondary response is considered as uncertainty.<p><p>Scaling laws allowing the extrapolation of the results obtained with existing 10m telescopes to future ELTs and even future larger telescopes are addressed and the most relevant parameters are highlighted. The study is illustrated with a set of examples of increasing sizes, up to 200 segments. This numerical study confirms that scaling laws, originally developed with simple analytical models, can be used in confidence in the preliminary design of large segmented telescopes. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Tesis por compendio / [ES] Los servicios ecosistémicos de montaña han adquirido importancia entre los científicos, los administradores y los encargados de formular políticas de todo el mundo; sin embargo, las actividades humanas están amenazando su conservación, en particular los cambios en el uso del suelo debido al aumento de la urbanización, la expansión agrícola y la deforestación. La Puna Altoandina es un ecosistema montañoso representativo que enfrenta estos serios y crecientes desafíos. La Puna Altoandina, cuyos principales socioecosistemas consisten en pastizales naturales, matorrales y zonas agrícolas, puede proporcionar múltiples servicios ecosistémicos influenciados por el tipo de cobertura terrestre y sus dinámicas. En este contexto, se han explorado las dinámicas entre los usos representativos de la superficie terrestre y su potencial para proporcionar servicios ecosistémicos en la Puna húmeda Altoandina a lo largo del tiempo. Asimismo, se ha completado un análisis espacio-temporal que describe cómo diferentes patrones de 6 dinámicas de cambio del uso del suelo impactan en la provisión de 7 servicios ecosistémicos durante un período de 13 años (de 2000 a 2013), y en el territorio de 25 provincias. Además, con el fin de mejorar la gestión de los servicios ecosistémicos, abordamos los efectos de aplicar dos análisis "clúster" (estáticos y dinámicos) para evaluar los conjuntos de servicios ecosistémicos en cuatro escalas de observación diferentes (dos ámbitos administrativos y dos tamaños de pixel geográfico: 0.25 y 9 km2). En general, este estudio proporciona un enfoque para facilitar la incorporación de los servicios ecosistémicos a múltiples escalas que permite una interpretación fácil del desarrollo de la región y que puede contribuir a mejorar las acciones para la gestión del uso del suelo y las decisiones de política ambiental. / [CA] Els serveis ecosistèmics muntanya han adquirit importància entre els científics, els administradors i els encarregats de formular polítiques de tot el món; no obstant això, les activitats humanes estan amenaçant la seua conservació, en particular els canvis en l'ús del sòl a causa de l'augment de la urbanització, l'expansió agrícola i la desforestació. La Puna Altoandina és un ecosistema muntanyenc representatiu que enfronta aquests seriosos i creixents desafiaments. La Puna Altoandina que els seus principals soci-ecosistemes consisteixen en pasturatges naturals, matolls i zones agrícoles, pot proporcionar múltiples serveis ecosistèmics influenciats per les diferents categories de cobertura terrestre y els seus dinàmiques. En aquest context, s'han explorat les dinàmiques entre els usos representatius de la superfície terrestre i el seu potencial per a proporcionar serveis ecosistèmics en la Puna humida Altoandina al llarg del temps. Així mateix, s'ha completat una anàlisi espai-temporal que descriu com diferents patrons de 6 dinàmiques de canvi de l'ús del sòl impacten en la provisió de 7 serveis ecosistèmics durant un període de 13 anys (de 2000 a 2013), i en el territori de 25 províncies. A més, amb la finalitat de millorar la gestió dels serveis ecosistèmics, abordem els efectes d'aplicar dues anàlisis "clúster" (estàtics i dinàmics) per a avaluar els conjunts de serveis ecosistèmics en quatre escales d'observació diferents (dos àmbits administratius i dues grandàries de píxel geogràfic: 0.25 y 9 km2). En general, aquest estudi proporciona un enfocament per a facilitar la incorporació dels serveis ecosistèmics a múltiples escales que permet una interpretació fàcil del desenvolupament de la regió i que pot contribuir a millorar les accions per la gestió de l'ús del sòl i les decisions de política ambiental. / [EN] Mountain ecosystem services have gained relevance among scientists, managers, and policy-makers worldwide; but, human activities are threatening its conservation, particularly land changes due to increased urbanization, agricultural expansion and deforestation. The high-Andean Puna is a representative mountain ecosystem that is facing these serious and growing challenges. The high-Andean Puna, whose main socialecosystems consist of natural grassland, shrubland and agricultural areas, can provide multiple regulating ecosystem services influenced by the land cover/use type and their dynamics. In this context, we explored the dynamics between the representative land-cover classes and its potential to provide ecosystem services in the high-Andean moist Puna over time. We completed a spatiotemporal analysis that describes how different patterns of 6 landchange dynamics impact on the supply of 7 ecosystem services over a period of 13 years (from 2000 to 2013), and across 25 provinces. Moreover, in order to improve the management of ecosystem services, we addressed the effects of applying two cluster analyses (static and dynamic) for assessing bundles of ecosystem services across four different scales of observation (two administrative boundaries and two sizes of grids: 0.25 and 9 km2). Overall, this study provides an approach to facilitate the incorporation of ES at multiple scales allowing an easy interpretation of the region development that can contribute to land management actions and policy decisions. / Madrigal Martínez, S. (2021). Land-change dynamics and ecosystem services using expert-based assessment and GIS: methodological implications for improving decision-making [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172369 / Compendio