943 resultados para Tension loads
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The existing language situation in Kazakhstan, while peaceful, is not without some tension. We propose to analyze here some questions we consider relevant in the frame of cultural globalization and gender equality, such as: free from Russian imperialism, could Kazakhstan become an easy prey of Turkey’s “imperialist dream”? Could these traditionally Muslim people be soon facing the end of religious tolerance and gender equality, becoming this new old language an easy instrument for the infiltration in the country of fundamentalism (it has already crossed the boarders of Uzbekistan), leading to a gradual deterioration of its rich multicultural relations? The present structure of the language is still very fragile: there are three main dialects and many academics defend the re-introduction of the Latin alphabet, thus enlarging the possibility of cultural “contamination” by making the transmission of fundamentalist ideas still easier through neighbour countries like Azerbaijan, Uzbekistan and Turkmenistan (their languages belong to the same sub-group of Common Turkic), where the Latin alphabet is already in use, and where the ground for such ideas shown itself very fruitful.
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We have calculated the shapes of flat liquid films, and of the transition region to the associated Plateau borders (PBs), by integrating the Laplace equation with a position-dependent surface tension γ(x), where 2x is the local film thickness. We discuss films in either zero or non-zero gravity, using standard γ(x) potentials for the interaction between the two bounding surfaces. We have investigated the effects of the film flatness, liquid underpressure, and gravity on the shape of films and their PBs. Films may exhibit 'humps' and/or 'dips' associated with inflection points and minima of the film thickness. Finally, we propose an asymptotic analytical solution for the film width profile.
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The phase behaviour of a number of N-alkylimidazolium salts was studied using polarizing optical microscopy, differential scanning calorimetry and X-ray diffraction. Two of these compounds exhibit lamellar mesophases at temperatures above 50 degrees C. In these systems, the liquid crystalline behaviour may be induced at room temperature by shear. Sheared films of these materials, observed between crossed polarisers, have a morphology that is typical of (wet) liquid foams: they partition into dark domains separated by brighter (birefringent) walls, which are approximately arcs of circle and meet at "Plateau borders" with three or more sides. Where walls meet three at a time, they do so at approximately 120 degrees angles. These patterns coarsen with time and both T1 and T2 processes have been observed, as in foams. The time evolution of domains is also consistent with von Neumann's law. We conjecture that the bright walls are regions of high concentration of defects produced by shear, and that the system is dominated by the interfacial tension between these walls and the uniform domains. The control of self-organised monodomains, as observed in these systems, is expected to play an important role in potential applications.
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Philosophical Magazine Letters Volume 88, Issue 9-10, 2008 Special Issue: Solid and Liquid Foams. In commemoration of Manuel Amaral Fortes
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In Invisible Cities (1972), Italo Calvino contrasts a rigid outline structure with a flexible textual content. The tension comprised by the numerical structure proposed in the table of contents stands out against the set of polissemic texts which make up the subject matter of the book. The opposition between form and content point to a fruitful dichotomy in the conception of the novel linked to the theories of the open and closed work. This essay will investigate the structural construction of Invisible Cities by looking at its table of contents, seeking to discuss some models of formalistic representation proposed by the criticism and the specific contribution they may, or may not, provide. The objective is to analyse the pertinence of such theories in the light of historical and cultural approaches. Aiming to uncover possible meanings which arise from the debate, this essay will question to what extent structural complexities can be considered literary if they are not ultimately related to the culture in which a text is found.
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Conferência: 2nd Experiment at International Conference - 18-20 September 2013
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Relatório de Estágio para obtenção do grau de Mestre em Engenharia Civil
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Mestrado em Fisioterapia
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Dissertação de Natureza Científica elabora da no âmbito do protocolo de cooperação entre o ISEL e o LNEC para obtenção do grau de Mestre em Engenharia Civil
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In the proposed model, the independent system operator (ISO) provides the opportunity for maintenance outage rescheduling of generating units before each short-term (ST) time interval. Long-term (LT) scheduling for 1 or 2 years in advance is essential for the ISO and the generation companies (GENCOs) to decide their LT strategies; however, it is not possible to be exactly followed and requires slight adjustments. The Cournot-Nash equilibrium is used to characterize the decision-making procedure of an individual GENCO for ST intervals considering the effective coordination with LT plans. Random inputs, such as parameters of the demand function of loads, hourly demand during the following ST time interval and the expected generation pattern of the rivals, are included as scenarios in the stochastic mixed integer program defined to model the payoff-maximizing objective of a GENCO. Scenario reduction algorithms are used to deal with the computational burden. Two reliability test systems were chosen to illustrate the effectiveness of the proposed model for the ST decision-making process for future planned outages from the point of view of a GENCO.
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Adhesive bonding has become more efficient in the last few decades due to the adhesives developments, granting higher strength and ductility. On the other hand, natural fibre composites have recently gained interest due to the low cost and density. It is therefore essential to predict the fracture behavior of joints between these materials, to assess the feasibility of joining or repairing with adhesives. In this work, the tensile fracture toughness (Gc n) of adhesive joints between natural fibre composites is studied, by bonding with a ductile adhesive and co-curing. Conventional methods to obtain Gc n are used for the co-cured specimens, while for the adhesive within the bonded joint, the J-integral is considered. For the J-integral calculation, an optical measurement method is developed for the evaluation of the crack tip opening and adherends rotation at the crack tip during the test, supported by a Matlab sub-routine for the automated extraction of these quantities. As output of this work, an optical method that allows an easier and quicker extraction of the parameters to obtain Gc n than the available methods is proposed (by the J-integral technique), and the fracture behaviour in tension of bonded and co-cured joints in jute-reinforced natural fibre composites is also provided for the subsequent strength prediction. Additionally, for the adhesively- bonded joints, the tensile cohesive law of the adhesive is derived by the direct method.
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Component joining is typically performed by welding, fastening, or adhesive-bonding. For bonded aerospace applications, adhesives must withstand high-temperatures (200°C or above, depending on the application), which implies their mechanical characterization under identical conditions. The extended finite element method (XFEM) is an enhancement of the finite element method (FEM) that can be used for the strength prediction of bonded structures. This work proposes and validates damage laws for a thin layer of an epoxy adhesive at room temperature (RT), 100, 150, and 200°C using the XFEM. The fracture toughness (G Ic ) and maximum load ( ); in pure tensile loading were defined by testing double-cantilever beam (DCB) and bulk tensile specimens, respectively, which permitted building the damage laws for each temperature. The bulk test results revealed that decreased gradually with the temperature. On the other hand, the value of G Ic of the adhesive, extracted from the DCB data, was shown to be relatively insensitive to temperature up to the glass transition temperature (T g ), while above T g (at 200°C) a great reduction took place. The output of the DCB numerical simulations for the various temperatures showed a good agreement with the experimental results, which validated the obtained data for strength prediction of bonded joints in tension. By the obtained results, the XFEM proved to be an alternative for the accurate strength prediction of bonded structures.
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Dissertação para obtenção do grau de Mestre em Engenharia Electrotécnica Ramo de Energia
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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica
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Dissertação para a obtenção do grau de Mestre em Engenharia Electrotécnica Ramo de Energia