Malgré le cumul de connaissances sur le sujet du flambage des coques minces, des questions essentielles demeurent. En effet, malgré les avancées et une meilleure compréhension de l'effet des défauts, le dimensionnement continue de recourir aux anciennes règles qui découlent d'une démarche empirique et qui s'avèrent souvent trop conservatives comme c'est le cas par exemple pour la NASA SP8007 (1968). Cette règle est utilisée notamment pour le dimensionnement du lanceur Ariane 5. L'Etage Principal Cryogénique est en effet constitué de coques cylindriques minces, qui sont soumises à une combinaison de chargements et donc sujettes au déclenchement d'instabilités pouvant être catastrophiques. Il est ainsi nécessaire d'avoir une meilleure compréhension du phénomène pour pouvoir améliorer ces méthodes de dimensionnement dans le cas de coques moyennement longues (1 < L/R < 3) et minces (250 < R/t <1500). Nous employons pour cela une approche à la fois numérique et expérimentale. L'outil numérique est utilisé, via une modélisation pertinente, afin de construire une nouvelle règle de dimensionnement et d'étudier l'influence des différents paramètres (géométriques, matériau). L'aspect expérimental a pris une place prépondérante, une large campagne nous permettant de valider les résultats simulations pour différentes configurations, mais également d'avoir une bonne compréhension du phénomène. Ces deux aspects de notre recherche nous ont également permis de mieux déterminer l'interaction entre les différents chargements (pression interne, compression, flexion, cisaillement), plus ou moins comprise selon les cas.

[pt] Este trabalho apresenta um estudo do comportamento não- linear e instabilidade de cascas e painéis cilíndricos laminados de materiais compósitos. Com esta finalidade é desenvolvida uma formulação de alta ordem de deformação cisalhante que leva en conta estes efeitos nas relações deformação-deslocamento. O comportamento da casca é descrito por uma consistente teoria não-linear para cascas laminadas que considera pequenas deformações e rotações moderadas e incorpora automaticamente o efeito das deformações cisalhantes. O modelo de bifurcação clássico é utilizado para estudar a estabilidade da casca compósita. O comportamento pós-crítico é examinado a partir de uma solução modal obtida com técnicas de perturbação. Em ambos os casos aplica-se o método de Rayleigh-Ritz para discretizar o sistema de equações diferenciais de equilíbrio em um sistema de equações algébricas. O método de Newton-Raphson é empregado na resolução das equações não- lineares de equilíbrio do caminho pós-crítico e na obtenção do caminho fundamental da estrutura imperfeita. A implementação numérica (em álgebra simbólica) é feita utilizando a linguagem de programação Maple V release 3. É então desenvolvido um estudo paramétrico com o objetivo de determinar a influência dos parâmetros geométricos e das características próprias do laminado (número de lâminas e orientação das fibras) na resposta crítica e pós-crítica da casca compósita para dois tipos de carregamento, a saber: pressão lateral e compressão axial. É analisado, também, o grau de sensibilidade às imperfeições geométricas destas estruturas. São apresentadas comparações dos resultados teóricos aqui obtidos com outros existentes na literatura com o objetivo de demonstrar a confiabilidade da formulação e metodologia numérica aqui desenvolvidas. / [en] The purpose of the present work is to study the non-linear behaviour and instability of laminated composite cylindrical shells and panels under axial and pressure loading. The analysis is performed within a refined non- linear theory for composite laminated shells incorporating the effects of transverse shear and the geometric imperfections. The classical bifurcation theory is used to analyze the critical behavior of the shell. To examine the post-critical behavior of the shell, a modal solution based on the basic ideas of Koiter`s theory is deduced and the Rayleigh-Ritz method together with the Newton-Raphson strategy are used to solve the non-linear equilibrium problem and plot either the post-critical path or the non- linear equilibrium path of the imperfect shell. The analytical and numerical procedures were performed by the use of the symbolic algebra package Maple V release 3. The influence played by the geometrical parametrs of the shell and physical parameters of the composite laminate, such as stacking sequences and fiber orientation in each lamina, on the critical and post-critical behavior of the shell is examined and a series of conclusions are outlined. The imperfection sensitivity of these shells is also analyzed. Comparisons of the present results with those obtained by other theories and experiments are found to be satisfactory and show the validity of the present methodology. / [es] Este trabajo presenta un estudio de la inestabilidad y comportamiento no lineal y la inestabilidad de cortezas y paneles cilíndricos laminados de materiales compuestos. Con esta finalidad se desarrolla una formulación de alta orden de deformación cisallante que considera estos hechos en las relaciones deformación desplazamiento. EL comportamiento de la corteza se describe a través de una consistente teoría no lineal para cascas laminadas. Esta teoría considera pequeñas deformaciones y rotaciones moderadas e incorpora automáticamente las deformaciones cisallantes. El modelo de bifurcación clásico se utiliza para estudiar la estabilidad de la corteza. El comportamiento poscrítico se examina a partir de una solución modal obtenida con técnicas de perturbación. En ambos casos se aplica el método de Rayleigh Ritz para discretizar el sistema de ecuaciones diferenciales de equilibrio en un sistema de ecuaciones algébraicas. El método de Newton Raphson es utilizado en la resolución de las ecuaciones no lineares de equilibrio del camino postcrítico y en la obtención del camino fundamental de la extructura imperfecta. La implementación numérica (en álgebra simbólica) se realiza utilizando el lenguaje de programación Maple V release 3. Con el objetivo de determinar la influencia de los parámetros geométricos y de las características proprias del laminado en la respuesta crítica y postcrítica de la casca compósita, se realiza un estudio paramétrico para para dos tipos de carga: presión lateral y compresión axial. Se analiza también, el grado de sensibilidad a las imperfeiciones geométricas de estas extructuras. Finalmente, y con el objetivo de demostrar la confiabilidad de la formulación y la metodología numérica aqui desarrolladas, se comparan los resultados teóricos obtenidos con los reportados en la literatura.

The thesis on the topic Analysis of Faults Found in Fire Inspections Performed within Execution of State Fire Inspection by the Fire Brigade Rescue Corps of Southern Bohemia in 2003 2012 focuses on comparison of faults selected by gradual elimination from all the 700 fire inspections to final 150 complex fire inspections and classified per years in a ten-year comparison period. Follow-up inspections and thematic fire inspection were not used for the complex evaluation as they did not contain the necessary information. Six parameters were chosen from all the performed complex inspections containing 30 monitored facts of correctness and existence of documents of the inspected object and seven monitored facts from physical examination of the objects. These six parameters were subsequently compared. The aim of my thesis was to find out whether the numbers of the faults detected within execution of the state fire inspection were increasing in the individual categories. The theoretical part summarizes the basic legal norms applicable to the Fire Brigade Rescue Corps of the CR and to execution of the state fire inspection and some extensive legal norms related to the inspection activities or inspected subjects. Elaboration of the thesis topic required explanation of some terms like legal entity, private entrepreneur, fire inspection, state fire inspection and its integration in the Fire Brigade Rescue Corps of the CR. The chapter contains description of activities including graphs illustrating procedures related to execution of state fire inspection. A separate part is dedicated to fire protection history, formation of awareness of the history and to chronological arrangement of some key legal norms binding for the Fire Brigade Rescue Corps of the CR and execution of state fire inspection. It was for example necessary to present the rules governing execution of state fire inspection like professional competence of Fire Brigade Rescue Corps members and their identification at the place of inspection, to clarify the terms fire inspection plan and fire inspection programme. The final part of the theoretical base of the thesis contains the rules of behaviour of Fire Brigade Rescue Corps members performing state fire inspection at the inspected site and principles of interaction with people representing the inspected subject. The research methodology was chosen adequately to the topic dealt with. First archive materials from complex fire inspection records were studied and then the individual faults were qualitatively processed and categorized to faults in documentary part and physical defects. After that a selection of closer spectre of examined faults was performed and preparation of data for comparison. The faults of the individual years were compared in the monitored data and the danger index of the individual years was calculated. The concluding part of the thesis focused on presentation of the dependences of the detected faults of the individual years by means of tables and graphs. The results were mutually compared, classified, commented in detail in the discussion and elaborated into the overall image of the society. Dependence of the number of performed complex fire inspections on the number of detected faults was proven from the danger index and from graphic representation of its values.

This dissertation explores value-creation in interaction design through practical collaborations with studio craftspersons. A focus is on the meaning of “preciousness” from a design perspective – what I refer to as Making Preciousness –  which highlights aspects of material properties, design processes, and the attitude to the design space. Theoretically, the work takes inspiration from the Japanese philosophy of Wabi-Sabi, which is based on the fact that things are impermanent, incomplete, and imperfect. This reflects a view of preciousness beyond notions of practical use, luxury or monetary cost. In addition to theoretical studies, I engaged in practice-based research at the intersection of interaction design and studio crafts, in the domains of leather, silversmith and textile crafting. Through an approach that blends these practices with the making of interactive artefacts, preciousness for interaction design was explored. Through this work, I extract three qualities, all of which are closely linked to attributes and values ​​embedded in the craft practices examined. I refer to these as resourceful composition, material sensuality and the aiming for mattering artefacts. Resourceful composition refers to approaching a design space “resourcefully”, meaning that the designer actively values and uses the specific qualities of materials and tools consciously, for what they are suitable for. Material sensuality is about appreciating the sensory experience of interacting with materials, arriving through particular material qualities, such as texture, temperature or smell, but also interactive qualities. Aiming for mattering artefacts involves actively designing for impermanence, incompleteness and imperfection, and through that contributing to notions of preciousness through use, care, ownership and interaction between users and artefacts over time. The attitude of making preciousness can be seen as tying together materials and making with user experiences of computational artefacts. For interaction design, this points towards making processes in which computation and material knowledge, craftsmanship and aesthetic intentions are placed at the core. These values ​​relate to cultural, but also sensual experiences, which can be seen as under-explored in the design of interactive products. / <p>QC 20171213</p>

Ce sujet est d’actualité suite à une évolution rapide des types de conception de structures élancées utilisées dans les installations provisoires. C’est seulement depuis une vingtaine d’années que ces structures sont préfabriquées en cadres multidirectionnels (de sections tubulaires en acier ou en aluminium). Ces structures sont légères et leur stabilité réside seulement dans les raideurs internes au niveau des files de montants et au niveau horizontal par les planchers ainsi que dans les liaisons avec l’ouvrage. Ce travail concerne l’étude des instabilités (flambement-déversement) en tenant compte de différents types d’imperfections. De nouvelles courbes de flambement ainsi que les facteurs d’imperfection associés sont proposés dans cette thèse. Ces courbes sont obtenues en imposant une déformée initiale représentant les défauts géométriques et mécaniques (contraintes résiduelles). Les résultats expérimentaux confrontés avec les prévisions théoriques de l’Eurocode 3 montrent que les valeurs des imperfections figurant dans la littérature sont extrêmement exagérées. Les valeurs préconisées dans ce travail pourraient présenter un certain intérêt pour une modification éventuelle des courbes européennes de flambement pour ce type de structure. En ce qui concerne l’instabilité latérale, une méthodologie originale d’essais en vraie grandeur de poutres à treillis formés d’éléments tubulaires a été également mise au point. Le système de chargement à « roues libres » développé permet de libérer le point d’application de l’effort dès le début de l’instabilité. Cette technique conduit à des mesures plus précises du moment critique de déversement. / This subject becomes topical following a rapid evolution of design procedures for slender structures used widely in the temporary installations. Only through the last twenty years that these structures are prefabricated of multidirectional frames (steel or aluminium tubular sections). These structures are lightweight and their stability lies only in the internal stiffness at rows of posts and horizontally by the planking as well as the links with the building. This work concerns the study of instabilities (buckling - lateral torsional buckling) taking into account different types of imperfections. New buckling curves and the associated imperfection factors are proposed in this thesis. These curves are obtained by imposing an initial deformed representing the geometrical and mechanical defects (residual stress). The experimental results were confronted with theoretical predictions of Eurocode 3 which show that the values of the imperfections in the literature are extremely exaggerated. The values advocated in this work could be of interest for a possible adjustment of the European buckling curves for this type of structure. Regarding the lateral instability, an original methodology in real scale tests of trusses consist of tubular elements was also developed. The developed loading system of "free wheels" allows releasing the point of application of the force from the beginning of instability. This technique leads to more accurate measurements of the critical lateral torsional buckling moment.

Please read the abstract in the section 00front of this document / Thesis (PhD (Dogmatics and Christian Ethics))--University of Pretoria, 2007. / Dogmatics and Christian Ethics / PhD / unrestricted

Tension leveling is a process used in the steel industry in order to eliminate any shape imperfections of cold-rolled thin strips. The master thesis deals with developing a computer program that generates basic parameters of tension leveling line. The theoretical part of the thesis summarizes the types of the shape imperfections in strips, their causes and the principles of their elimination. This part also presents the mechanism of tension leveling and describes the present-day design of tension levelers. The practical part of the thesis starts with an analytical description of stress-strain behaviour of strip during tension leveling (supposing the simplified conditions). A computer program that allows devising basic parameters of tension leveling line is created on the basis of these analytical relations. The program results are successfully verified by numerical model based on the finite element method (FEM) created in the program ANSYS. Then the interdependencies of certain input and output parameters of created program are determined. These interdependencies can be used as effective design of tension leveling lines.

My project explores the possibilities of shaping space using lightweight textile-based elements. The focus is on the transformation of surface patterns into three-dimensional forms, using analogue parametric design with laser-cut beds as a main testbed. The result is a smorgasbord of prototypes: spatial configurations that divide and define space. Each design is a permeable three-dimensional form that projects a unique pattern of shadow and light. The basis of my project comes from an initial investigation of Uppsala public libraries’ needs for flexible solutions. The libraries have housed many civic activities that I have experienced in recent years since moving to Uppsala in 2018. With their requirement of multiple types of use, I propose using fabric infrastructure as configurable room dividers. I use discarded textile (used carpets, fabric remnants) as the starting point for each prototype. The material itself imposes certain restrictions on the work. Each new piece of fabric acquired a problem waiting for a solution. In this sense, the finished prototype constitutes a solved puzzle. One key objective is to create designs that are flexible while still being robust enough to be portable. Another key objective is to create inviting and organic designs. While I used laser cutters to cut the fabric into precise patterns, I allowed gravity and light to create an imperfect and organic end-result. However, the outcome of my experimental exploration is a system and a technique for making use of discarded textile materials to create atmospheres and spaces.

Charles University in Prague Faculty of Social Sciences Institute of Economic Studies MASTER THESIS An Experimental Test of Design Alternatives for Spectrum Auctions with Communication Channels Author: Bc. Jindřich Matoušek Supervisor: PhDr. Lubomír Cingl Academic Year: 2013/2014 Abstract The multi-unit auction mechanisms are one of the most important instruments used for the allocation of spectrum licenses, airport time slots, delivery routes, networking or furniture allocation. This thesis experimentally examines the attributes of complex multi-unit auction mechanisms (Simultaneous Multi-Round Auction and its combinatorial extension Simultaneous Multi-Round Package Bidding) in the presence of an opportunity to collude among the bidding participants due to a provision of a simple communication channel - a chat window. The results suggest that in our parameter setting, the combinatorial bidding format does not bring higher efficiency. Interestingly, allowing for communication increases efficiency in both examined auction formats. Bidders are able to split the auctioned goods in a collusive agreement, which results in a better allocation compared to the auction formats without the communication channel. Combinatorial bidding on packages probably makes the decision-making problem of bidders hard to process...

La tesi, costituita da due parti e tre capitoli, si concentra sulle conseguenze macroeconomiche della globalizzazione, prendendo in considerazione vari schemi di un modello a generazioni sovrapposte, in un mercato finanziario integrato. Per ipotesi, gli agenti vivono per due periodi e sono divisi in due gruppi: i "vecchi" che posseggono il fattore capitale e i "giovani" che offrono lavoro e risparmio. Nella prima parte si suppone che i mercati siano perfetti. Dopo aver ricevuto il loro reddito, i giovani ottimizzano consumo e risparmio. Diverse ipotesi vengono avanzate sull'apertura dei mercati, ma le economie convergono sempre verso uno stato stazionario asintoticamente stabile. Nella seconda parte i mercati finanziari sono imperfetti e i prestiti sono razionati. I giovani agenti risparmiano tutto il loro reddito e consumano solo nel secondo periodo della loro vita. In queste nuove ipotesi si possono riscontrare dinamiche endogene di tipo periodico. / The essay, made by two parts and three chapters, focuses on macroeconomic effects of globalization, considering various schemes of a two-country OLG model with integrated financial market. For hypothesis, agents live for two periods and are divided in two groups: the "old" that own the capital factor and the "young" that supply labor and savings. In the first part markets are supposed to be perfect. After received their income, the young optimize their consumption and savings. Different hypotheses about the opening markets are considered, but the economies ever converge to an asymptotically stable steady state. In the second part the financial markets are imperfect and borrowing is constrained. The young agents save all their income and consume only in the second period of their life. In these new hypotheses endogenous, periodic dynamics may occur.