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Dans cette thèse, on étudie l’effet de l’imperfection de marché sur la stabilité macroéconomique dans le modèle standard de Ramsey et celui de OLG. pour effectuer cette objective, on utilise la méthode de l’analyse de dynamique local lancé par Grandmont, Pintus et De Vilder (1998). les imperfections qu’on utilise sont les externalités en consommation, imperfection dans le marche de crédit, la présence de taxe progressive sur le revenu salariel et l’existence de coût de transaction associé avec l’accumulation de capital. / In this thesis, we study the effect of market imperfection on macroeconomic stability in the standard Ramsey model and that of the Olg. In order to achieve this objective, we use the local analysis method pioneered by Grandmont, Pintus and De Vilder (1998). The imperfections used in this thesis are the consumption externalities, credit market imperfections, progressive labor-income taxation policy and the presence of transaction costs associated with capital accumulations.

While investigating incidents where imperfection improves the whole instead of ruining it—across disciplines including animation, particle physics, and rug making—the narrator of “Botched” remembers an early childhood trauma, and explores how this flaw might have shaped her own life. “Botched” is a literary exploration into the heart of imperfection, blending fiction, nonfiction, memoir, and photography.

The recent development in the marine industry with largerships built in sandwich construction and also the use of moreadvanced materials has enforced improvements of design criteriaregarding wrinkling. The commonly used Hoff’s formula isnot suited for the highly anisotropic fibre reinforced sandwichface sheets of today. The work presented herein investigates the wrinklingphenomenon. A solution to wrinkling of anisotropic sandwichplates subjected to multi-axial loading is presented. Thesolution includes the possibility of skew wrinkling where thewrinkling waves are not perpendicular to the principal loaddirection. The wrinkling angle is obtained from the solutiontogether with the maximum wrinkling load. This method has beensupported with tests of anisotropic plates subjected touni-axial and bi-axial loading. The effect of the face sheet local bending stiffness showsthe importance of including the face sheet stacking sequence inthe wrinkling analysis. The work points out the influence ofthe face sheet local bending stiffness on wrinkling. Threedifferent means of improving the wrinkling load except changingcore material is evaluated. The effect of the differentapproaches is evaluated theoretically and also throughcomparative testing. The transition between wrinkling and pureface sheet compression failure is investigated. Theoreticaldiscussions are compared with compressive test results of twodifferent face sheet types on seven different core densities.The failure modes are investigated using fractography. Theresults clearly show how the actual sandwich compressionfailure mode is influenced by the choice of core material,changing from wrinkling failure to face sheet micro bucklingfailure as the modulus density increases. Finally, a new approach is presented where the wrinklingproblem is transferred from a pure stability problem to amaterial strength criterion. The developed theory providesmeans on how to decide which sandwich constituent will failfirst and at which load it will fail. The method give insightto and develop the overall understanding of the wrinklingphenomenon. A very good correlation is found when the developedtheory is compared with both finite element calculations and toexperimental tests. <b>Keywords:</b>wrinkling, local buckling, imperfection,stability, anisotropy, sandwich

<p>The recent development in the marine industry with largerships built in sandwich construction and also the use of moreadvanced materials has enforced improvements of design criteriaregarding wrinkling. The commonly used Hoff’s formula isnot suited for the highly anisotropic fibre reinforced sandwichface sheets of today.</p><p>The work presented herein investigates the wrinklingphenomenon. A solution to wrinkling of anisotropic sandwichplates subjected to multi-axial loading is presented. Thesolution includes the possibility of skew wrinkling where thewrinkling waves are not perpendicular to the principal loaddirection. The wrinkling angle is obtained from the solutiontogether with the maximum wrinkling load. This method has beensupported with tests of anisotropic plates subjected touni-axial and bi-axial loading.</p><p>The effect of the face sheet local bending stiffness showsthe importance of including the face sheet stacking sequence inthe wrinkling analysis. The work points out the influence ofthe face sheet local bending stiffness on wrinkling. Threedifferent means of improving the wrinkling load except changingcore material is evaluated. The effect of the differentapproaches is evaluated theoretically and also throughcomparative testing. The transition between wrinkling and pureface sheet compression failure is investigated. Theoreticaldiscussions are compared with compressive test results of twodifferent face sheet types on seven different core densities.The failure modes are investigated using fractography. Theresults clearly show how the actual sandwich compressionfailure mode is influenced by the choice of core material,changing from wrinkling failure to face sheet micro bucklingfailure as the modulus density increases.</p><p>Finally, a new approach is presented where the wrinklingproblem is transferred from a pure stability problem to amaterial strength criterion. The developed theory providesmeans on how to decide which sandwich constituent will failfirst and at which load it will fail. The method give insightto and develop the overall understanding of the wrinklingphenomenon. A very good correlation is found when the developedtheory is compared with both finite element calculations and toexperimental tests.</p><p><b>Keywords:</b>wrinkling, local buckling, imperfection,stability, anisotropy, sandwich</p>

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Hui and Chen (1986) were the first to show that the well-known Koiter’s General Theory of Elastic Stability of 1945 can be significantly improved by evaluating the postbuckling b coefficient at the actual applied load, rather than at the classical buckling load. Such improvement method was demonstrated to be (1) very simple to apply with no tedious algebra, (2) significant reduction in imperfection sensitivity and (3) although it is still asymptotically valid, there exists a significant extension of the range of validity involving larger imperfection amplitudes. Strictly speaking, Koiter’s theory of 1945 is valid only for vanishingly small imperfection amplitudes. Hence such improved method is termed Hui’s Postbuckling method. This study deals with the postbuckling and imperfection sensitivity of different kinds of cylinders, using the Hui’s postbuckling method. For unstiffened cylinder and laminate cylinder the results are compared with ABAQUS simulation results, and a parameter variation of stringer/ring stiffened cylinder is also evaluated. A significant positive shift of the postbuckling b coefficient is found which indicates that Koiter's general stability theory of 1945 has significantly overestimated the imperfection sensitivity of the structure. Also, compared with the Koiter's general stability theory, the valid region is significantly increased by using Hui's postbuckling method.

The main purpose of this practice-led research is to explore the relevance of present day Taiwanese aboriginal weavers’ work to contemporary society and how it might be integrated into today’s production processes, and used on stage as well as in exhibition. My research focuses on my costume design work for two theatrical productions, Africussion and Romeo and Juliet, for which the costumes were made with traditional Taiwanese aboriginal woven textiles, and is based on the assumption that the process of costume design affords a space to explore other aesthetic possibilities for aboriginal woven textiles, and that the theatre provides a context in which the conventional conceptions of Taiwanese aboriginal textile design can be challenged, broken apart and renewed. This research deals with both the theoretical and the practical considerations that apply to aboriginal weaving, and examines the intellectual traditions of the philosophy of art and aesthetics to be found in its theory and application. My thesis challenges the notion upheld by many of today’s aboriginal weavers that their ‘traditions’ are fixed and unchangeable, and argues for the importance of individual creativity if modern, contemporary needs and tastes in textiles are to be met by materials woven in the aboriginal way. My practice-led research is grounded on the techniques of aboriginal backstrap loom and weaving and basket weaving, which were learned from aboriginal weavers in a 20-month tribal fieldwork. This project approaches aboriginal woven textiles as artistic objects in the context of theatre productions and performances instead of as mere commercial entities. It also argues that theatrical costume design is much more than just the making of simple costumes that complement performances.

The advancement of the structural steel manufacturing industry has led to the recent emergence of steel members with Elliptical Hollow Sections (EHS) and Semi Elliptical Hollow Sections (SEHS). Although these sections are gaining popularity among architects, the lack of design guidelines specifically tailored towards these sections inhibits their efficient structural use. Within this context, this thesis provides several steps towards the development of such guidelines. A review of the manufacturing process of hot-rolled steel sections is conducted with emphasis on hollow structural sections. The main factors affecting the formation of residual stresses during cooling of the sections are discussed. Lower bound plastic interaction relations for EHS subjected to combinations of axial force, bi-axial bending moments and torsion are then derived. The formulation is based on the lower bound theorem of plasticity and the maximum distortional energy density yield criterion. Its applicability for conducting the cross-sectional interaction check in structural steel design problems is illustrated through a practical example. A simplified and conservative interaction equation is then proposed based on curve fitting of the results of the lower bound solution. Upper bound interaction relations are next developed for EHS subjected to combinations of axial force, bi-axial bending moments, torsion and bimoments. The formulation is based on kinematically admissible strain fields within the context of the upper bound theorem of plasticity. The interaction relations derived successfully capture the effect of confining radial strains present at welded end sections, as well as sections that are free to deform in the radial direction away from end welded sections. An iterative solution technique is developed to solve the resulting highly non-linear system of interaction relations. The effects of residual stresses and initial imperfections on axial compressive resistance of hot-rolled EHS are then incorporated into the lower bound interaction relations. Towards that goal, the thermo-mechanical properties of steel were extracted from the literature. A thermo-mechanical finite element model was developed for prediction of residual stresses in rolled sections. The validity of the model was assessed by comparison against residual stress measurements available in the literature. The model is then applied to predict the residual stresses in hot-rolled EHS. A series of geometric and material nonlinear finite element analyses is conducted on columns of EHS sections. The analyses include predicted residual stresses and initial out-of-straightness imperfections in order to determine the inelastic buckling capacity of EHS members and generate column curves for EHS sections. The column curves are subsequently compared to those based on Canadian, American and European design codes. Two column curve equations are proposed in a format similar to that of the Canadian Standards for buckling about major and minor axes. The column curves were subsequently combined with the interaction relations developed to provide design rules for EHS members under combined loads. The last contribution of the thesis provides a formulation of lower bound interaction relations for SEHS subject to combinations of axial force, bi-axial bending moments and torsion. An iterative scheme for solving the parametric form of the interaction relations is developed and a grid of admissible stress resultant combinations is generated. A series of trial functions are fitted to the grid of internal force combinations and two simplified and conservative interaction equations are proposed.