This thesis deals with building survey and diagnostics of residential house in Brno, which since its construction showed extensive faults. The theoretical presents to the general issue of building technical surveys, diagnostics reinforced concrete structures and describes methods for diagnosis of reinforced concrete structures. Practical part deals with building survey and diagnostics of the object including static assessment. Overall assessment is given in the conclusion.

The goal of this master thesis is to develop an algorithm for solving cables on pulleys, which would be more efficient and accurate than existing algorithm used in software RFEM. This algorithm was integrated to the program for static and dynamic analysis of structures, in the form of particular program module. This work also contains examples of using this algorithm. The comparison of expected results with outcomes from the program is presented. The suitability for common practise is examined based on this comparison. The examples showed that the new algorithm for solving of cables on pulleys is more powerful and more accurate than existing solutions and most likely does not has equivalent competition.

<div>Learning practices in education are constantly evolving to provide high-quality education. One of the trends used to provide high-quality education is incorporating technological tools to teach and learn STEM concepts. Implementing physical manipulative tools and virtual manipulative tools in STEM classrooms positively influenced conceptual learning. Furthermore, visuohaptic simulations are learning tools that combine physical and virtual manipulative affordances in a single learning experience. For investigating the value of visual and haptic feedback in virtual environments, we designed an embodied learning experience where learners used a hands-on tool for learning friction concepts. The theoretical framework of embodied learning guided the design of the learning tools and the research design. The learning tools were visuohaptic simulations and physical manipulative tool. Results suggested no influence in conceptual knowledge of the physical manipulative tool. On the opposite, results suggested a positive influence of the visuohaptic simulation on conceptual knowledge. Moreover, our studies suggested that learners exposed to enhanced visual feedback and haptic feedback used two different mechanisms for improving friction conceptual knowledge. When enhanced visual feedback was activated, learners read the cubes' forces from the computer screen for correcting their answer or reinforce their correct knowledge. When haptic feedback was activated, learners inferred about the cubes' forces from the haptic feedback for correcting their answer or reinforce their correct knowledge. In a sequenced approach of feedback of haptic to haptic + enhanced visual, learners obtained the benefits of the haptic and visual feedback for learning friction. </div><div> </div>

Crack propagation studies in nanocrystalline alpha-iron samples with grain sizes ranging from 6 to 12 nm are reported at temperatures ranging from 100K to 600K using atomistic simulations. For all grain sizes, a combination of intragranular and intergranular fracture is observed. Mechanisms such as grain boundary accommodation, grain boundary triple junction, grain nucleation and grain rotation are observed to dictate the plastic deformation energy release. Intergranular fracture is shown to proceed by the coalescence of nanovoids formed at the grain boundaries ahead of the crack. The simulations also show that at an atomistic scale the fracture resistance and plastic deformation energy release mechanisms increase with increasing temperature. Finally a softening of the material occurs with decreasing grain size. The elastic properties are found to decrease and the fracture resistance to increase with decreasing grain size. / Master of Science

We propose a novel analytic approach for the comparative statics analysis of operations management problems on the capacity investment decision and the influenza (flu) vaccine composition decision. Our approach involves exploiting the properties of the underlying mathematical models, and linking those properties to the concept of stochastic orders relationship. The use of stochastic orders allows us to establish our main results without restriction to a specific distribution. A major strength of our approach is that it is "scalable," i.e., it applies to capacity investment decision problem with any number of non-independent (i.e., demand or resource sharing) products and resources, and to the influenza vaccine composition problem with any number of candidate strains, without a corresponding increase in computational effort. This is unlike the current approaches commonly used in the operations management literature, which typically involve a parametric analysis followed by the use of the implicit function theorem. Providing a rigorous framework for comparative statics analysis, which can be applied to other problems that are not amenable to traditional parametric analysis, is our main contribution. We demonstrate this approach on two problems: (1) Capacity investment decision, and (2) influenza vaccine composition decision. A comparative statics analysis is integral to the study of these problems, as it allows answers to important questions such as, "does the firm acquire more or less of the different resources available as demand uncertainty increases? does the firm benefit from an increase in demand uncertainty? how does the vaccine composition change as the yield uncertainty increases?" Using our proposed approach, we establish comparative statics results on how the newsvendor's expected profit and optimal capacity decision change with demand risk and demand dependence in multi-product multi-resource newsvendor networks; and how the societal vaccination benefit, the manufacturer's profit, and the vaccine output change with the risk of random yield of strains. / Ph. D.

Entre as peças fundamentais que compõem as estruturas de concreto armado encontram-se as lajes, as quais vêm sendo objeto de contínuo aperfeiçoamento no que diz respeito ao conforto, à segurança e à economia. O desenvolvimento de técnicas construtivas econômicas propiciou o aparecimento das lajes pré-fabricadas, com vantagens em relação às lajes maciças, como: redução do consumo de madeira para as fôrmas, redução do consumo de concreto, com a conseqüente diminuição dos esforços nas peças estruturais, e nas fundações. Tudo isto redundando evidentemente em menor tempo de execução e maior economia no custo da construção. Procurou-se neste trabalho reunir informações que possibilitem uma visão global sobre o tema, abordando-se, para isso, aspectos históricos das lajes pré-fabricadas, descrição dos elementos que as compõem, estudo do processo construtivo, dimensionamento, ensaios de laboratório em vigas com armaduras treliçadas e, finalmente, a análise da segurança destas lajes na fase de construção. Esta pesquisa mostrou que a qualidade e o desempenho estrutural destas lajes depende, em grande parte, dos cuidados tomados durante a fase construtiva, especialmente no que diz respeito ao escoramento. Assim, consegue-se evitar acidentes em obras ocasionados por erros cometidos nessa etapa. / Among the fundamental elements of reinforced concrete structures, slabs have been the object of continuous improvement regarding of comfort, safety and economy. The development of economical construction techniques has permitted the forecoming of precast slabs, with advantages over massive slabs, such as: reducing the consumption of formwork, concrete, and consequently a reduction of the stress on the structural elements and foundations. All these, obviously, result in quicker execution and greater economy in construction costs. This study has attempted to gather the necessary information to provide a global view of this subject; approaching historical aspects of precast slabs, a description of its elements and construction process, dimensioning, laboratory experiments upon truss-framed reinforced beams, and finally, an analysis of security in the construction phase. It was concluded that the quality and structural performance of these slabs depend greatly on the care taken during the construction phase, particulary in respect to bracing. Thus, accidents caused by errors comitted at this stage are avoided.

The present work uses statistical mechanics tools to investigate the dynamics of markets, prices, trades and wealth distribution. We studied the evolution of market dynamics in different stages of historical development by analyzing commodity prices from two distinct periods : ancient Babylon, and medieval and early modern England. We find that the first-digit distributrions of both Babylon and England commodity prices follow Benford's Law, indicating that the data represent empirical observations typically arising from a free market. Further, we find that the normalized prices of both Babylon and England agricultural commodities are characterized by stretched exponential distributions, and exhibit persistent correlations of a power law type over long periods of up to several centuries, in contrast to contemporary markets. Our findings suggest that similar market interactions may underlie the dynamics of ancient agricultural commodity prices, and that these interactions may remain stable across centuries. To further investigate the dynamics of markets, we present the analogy between transfers of money between individuals and the transfer of energy through particle collisions by means of the kinetic theory of gases. We introduce a theoretical framework of how micro rules of trading lead to the emergence of income and wealth distribution. Particularly, we study the effects of different types of distribution of savings/investments among individuals in a society and different welfare/subsidies redistribution policies. Results show that while considering savings propensities, the models approach empirical distributions of wealth quite well. The effect of redistribution better captures specific features of the distributions which earlier models failed to do. Moreover, the models still preserve the exponential decay observed in empirical income distributions reported by tax data and surveys. / by Natalia E. Romero. / Vita. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.

The materials that exhibit martensite transformation have very important applications in engineering, and the microstructures of the materials play a key role foraffecting their mechanical behavior in macroscope. Therefore many attentions havebeen drawn for studying the related problems. This work focuses on the motion oftwin boundaries. Three questions are being asked: how is a twin boundary is nucleated in a homogenous (untwinned) material? After the twin boundary is nucleated,how is its motion initiated? How fast does it move? This study provides an atomisticunderstanding for these three questions. Linear stability analysis is firstly applied to capture the initiation of motion of atwin boundary. When a twin boundary is about to move, the lowest eigenvalue of thesystem Hessian drops to zero. And the corresponding eigenvector predicts accuratelythe way in which the twin boundary is going to move. The same idea is applied toinvestigate how motion of an irrational twin boundary is initiated. Atomic modelsof irrational twin boundaries are constructed by employment of continuum models,provided that the point group of rotations which relate two variants is extended toany rotations in plane. The zero eigenvectors reveal the complicated behavior ofmotion of irrational twin boundaries. The problem of nonuniqueness of kinetic relations proposed by Schwetlick andZimmer is solved in a thermoelasticity framework. By calculating the net heat fluxcrossing the phase boundary which is carried by the phonons, a unique kinetic relationcan be determined. Finally, a nonlocal criterion for nucleation of twin boundariesis proposed. By checking the stiffness of each unit cell evaluated with respect to asingle variable that represents the displacement along the unit cell diagonal direction,locations and the orientations of nucleated twin boundaries can be predicted.

This research work focuses on the reactive power compensation of the permanent magnet synchronous generator (PSG) in wind power plants. PSG feeds a fixed voltage dc grid through a rectifier bridge. In variable speed operation, the PSG will be able to build torque only in small speed range. This is due to the fixed magnet of the PSG. External reactive power compensation provides an attractive solution to overcome this problem. Different reactive power compensation configurations were examined. Statics synchronous series compensation and a shunt passive filter were chosen as a compensation method. Simulation and implementation of small wind power plant were performed. The wind power plant consists of the synchronous generator, inverter, rectifier, coupling transformers and shunt passive filter. The experimental results agree to the proposed theory and simulation results. / Der Schwerpunkt meiner Promotion ist die Blindleistungskompensation bei einem permanenterregten Synchrongenerator. Der Synchrongenerator speist das Gleichsspannungsnetz über ein Gleichrichter. In der Drehzahlvariablen Betriebsverhalten können Nachteile auftreten. Die Folge ist, dass bei konstanter Gleichspannung und fester Erregung durch die Permanenterregung nur ein sehr kleiner Drehzahlbereich mit vernünftiger Drehmomentausbeute bedienbar ist. Ein möglicher Ausweg wäre eine variable Kompensationsspannung. Verschiedene Kompensationsverfahren wurden untersucht. Ein Series Active Filter und ein Shunt Passive-Filter wurden als Blindleistungskompensation gewählt. Im Rahmen meiner Dissertation beschäftige ich mich mit dem Aufbau und der Simulation einer Windkraftanlage. Diese besteht aus einem permanenterregten Synchrongenerator, einem Wechselrichrter, einem Gleichrichter, drei Transformatoren und einem passiven Filter. Das Versuchsergebnis zeigt, dass die Theorie mit der Simulation übereinstimmt.

Les structures fibreuses, formées d'une assemblée d'objets longilignes flexibles, sont très présentes dans notre environnement quotidien, notamment dans des systèmes biologiques tels que les végétaux ou les cheveux. Ces dernières années ont vu se développer diverses techniques de numérisation de la géométrie de fibres, soit par synthèse manuelle, soit par capture automatique. Parallèlement, de nombreux modèles physiques de simulation dynamique de fibres enchevêtrées ont été créés pour animer automatiquement ces objets complexes. Le but de cette thèse est d'établir un pont entre ces deux domaines: la géométrie de fibres d'une part, leur simulation dynamique d'autre part. Plus précisément, nous nous intéressons à la mise en correspondance d'une géométrie de fibres donnée en entrée, représentant un système mécanique à l'équilibre stable sous l'action de forces extérieures (gravité, forces de contact), avec les paramètres d'un modèle physique de fibres en contact. Notre objectif est de calculer les paramètres physiques des fibres de manière à garantir l'état d'équilibre de la géométrie donnée. Nous proposons de résoudre ce problème en choisissant comme modèle physique de fibres une assemblée de super-hélices en contact frottant. Nous proposons deux contributions principales. La première répond au besoin de convertir la géométrie d'une fibre numérisée quelconque, représentée comme une courbe 3d, en la géométrie du modèle des super-hélices, à savoir une courbe $G^1$ en hélices par morceaux. Nous proposons pour cela l'algorithme des tangentes flottantes 3d, qui consiste, en s'appuyant sur la condition de co-hélicité récemment énoncée par Ghosh, à interpoler N+1 tangentes réparties sur la courbe d'origine par N morceaux d'hélice, tout en minimisant l'écart en position. Par ailleurs nous complétons la démonstration partielle de Ghosh pour prouver la validité de notre algorithme dans le cas général. L'efficacité et la précision de notre méthode sont ensuite mises en évidence sur des jeux de données variés, d'abord synthétiques, créés par une artiste, puis issus de la capture de données réelles telles que des cheveux, des fibres musculaires ou des lignes de champ magnétique stellaire. Notre seconde contribution est le calcul de la géométrie au repos du modèle physique d'une assemblée de super-hélices, de sorte que la configuration de ce système à l'équilibre sous l'action des forces extérieures corresponde à la géométrie d'entrée. D'abord, nous considérons une fibre isolée soumise à des forces dérivant d'un potentiel, et montrons que le calcul est trivial dans ce cas. Nous proposons alors un critère simple permettant de décider si l'état d'équilibre est stable, et dans le cas contraire, de le stabiliser. Ensuite, nous considérons une assemblée de fibres soumises à des forces de contact frottant, modélisées par la loi non-régulière de Signorini-Coulomb. En considérant le matériau homogène, de masse et de raideur connues, et en nous appuyant sur une estimation de la géométrie au repos, nous construisons un problème d'optimisation quadratique convexe avec contraintes du second ordre. Nous montrons que ce problème inverse peut être résolu efficacement en utilisant un solveur conçu initialement pour le problème dynamique direct. Pour une géométrie d'entrée constituée de quelques milliers de fibres soumises à plusieurs dizaines de milliers de contacts frottants, nous calculons en quelques secondes une approximation plausible de la géométrie au repos des fibres, ainsi que des forces de contact en jeu. Nous appliquons finalement la combinaison de nos deux contributions à la synthèse automatique de coiffures physiques. Notre méthode permet d'initialiser un moteur physique de cheveux avec la géométrie issue des captures de coiffures réelles les plus récentes, et d'animer ensuite ces coiffures. / Fibrous structures, which consist of an assembly of flexible slender objects, are ubiquitous in our environment, notably in biological systems such as plants or hair. Over the past few years, various techniques have been developed for digitalizing fibers, either through manual synthesis or with the help of automatic capture. Concurrently, advanced physics based models for the dynamics of entangled fibers have been introduced in order to animate these complex objects automatically. The goal of this thesis is to bridge the gap between those two areas: on the one hand, the geometric representation of fibers; on the other hand, their dynamic simulation. More precisely, given an input fiber geometry assumed to represent a mechanical system in stable equilibrium under external forces (gravity, contact forces), we are interested in the mapping of such a geometry onto the static configuration of a physics-based model for a fiber assembly. Our goal thus amounts to computing the parameters of the fibers that ensure the equilibrium of the given geometry. We propose to solve this inverse problem by modeling a fiber assembly physically as a discrete collection of super-helices subject to frictional contact. We propose two main contributions. The first one deals with the problem of converting the digitalized geometry of fibers, represented as a space curve, into the geometry of the super-helix model, namely a $G^1$ piecewise helical curve. For this purpose we introduce the 3d floating tangents algorithm, which relies upon the co-helicity condition recently stated by Ghosh. More precisely, our method consists in interpolating N+1 tangents distributed on the initial curve by N helices, while minimizing points displacement. Furthermore we complete the partial proof of Ghosh for the co-helicity condition to prove the validity of our algorithm in the general case. The efficiency and accuracy of our method are then demonstrated on various data sets, ranging from synthetic data created by an artist to real data captures such as hair, muscle fibers or lines of the magnetic field of a star. Our second contribution is the computation of the geometry at rest of a super-helix assembly, so that the equilibrium configuration of this system under external forces matches the input geometry. First, we consider a single fiber subject to forces deriving from a potential, and show that the computation is trivial in this case. We propose a simple criterion for stating whether the equilibrium is stable, and if not, we show how to stabilize it. Next, we consider a fiber assembly subject to dry frictional contact (Signorini-Coulomb law). Considering the material as homogeneous, with known mass and stiffness, and relying on an estimate of the geometry at rest, we build a well-posed convex quadratic optimization problem with second order cone constraints. For an input geometry consisting of a few thousands of fibers subject to tens of thousands frictional contacts, we compute within a few seconds a plausible approximation of both the geometry of the fibers at rest and the contact forces at play. We finally apply the combination of our two contributions to the automatic synthesis of natural hairstyles. Our method is used to initialize a physics hair engine with the hair geometry taken from the latest captures of real hairstyles, which can be subsequently animated physically.