3,112 research outputs found

    An Optimization of the Maintenance Assets Distribution Network in the Argentine Air Force

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    The Argentine Air Force Materiel General Directorate is responsible for the supply and distribution of reparable and consumable assets to support the operations of more than thirty different weapons systems. The Materiel General Directorate recently initiated an effort to assure logistic support and to gradually increase the productivity and efficiency of the related processes. The distribution of consumable and reparable assets was a key process identified as inefficient and targeted for improvement, and a recommendation was made to consider organic or private transportation and reduce transportation time in order to improve responsiveness and drive down logistic pipeline costs. This thesis uses network flow modeling methods to analyze the spare parts flows between Argentine Air Force units to determine overall transportation demand and capacity required for a defined level of service, and to evaluate the tradeoffs between costs and service levels. The goal is to assist in the development of an effective and efficient maintenance assets distribution network

    Superando la "trampa del ingreso medio": El caso de Chile

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    This article analyzes the concept of the middle income trap. First, it focuses on Latin America, since the region is home to several cases of this phenomenon, and demonstrates the different struggles that cross several nations to overcome. The way in which other regions, such as Asia Pacific, have treated average income, is also analyzed. Then, the article focuses on Chile and analyzes the behavior of this phenomenon in the southern country, to conclude that while Chile has come a long way to progress and reach high levels of income, there are still several aspects that its economy must change to to escape the problem involved in the middle income trap.El presente art√≠culo analiza el concepto de la trampa del ingreso medio. Primero se enfoca en Am√©rica Latina, ya que la regi√≥n alberga varios casos de dicho fen√≥meno, y demuestra las diferentes luchas que atraviesan varias naciones para superarlo. Tambi√©n se analiza la manera en que otras regiones, como Asia Pac√≠fico, han tratado el ingreso medio. Luego, el art√≠culo se enfoca en Chile y analiza el comportamiento de este fen√≥meno en el pa√≠s austral, para concluir que si bien Chile ha recorrido un largo camino para progresar y alcanzar niveles altos de ingreso, a√ļn hay varios aspectos que su econom√≠a debe cambiar para poder escapar a la problem√°tica que implica la trampa del ingreso medio

    Frobenius pairs in abelian categories: correspondences with cotorsion pairs, exact model categories, and Auslander-Buchweitz contexts

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    In this work, we revisit Auslander-Buchweitz Approximation Theory and find some relations with cotorsion pairs and model category structures. From the notions of relatives generators and cogenerators in Approximation Theory, we introduce the concept of left Frobenius pairs (X,ŌČ)(\mathcal{X},\omega) in an abelian category C\mathcal{C}. We show how to construct from (X,ŌČ)(\mathcal{X},\omega) a projective exact model structure on X‚ąß\mathcal{X}^\wedge, as a result of Hovey-Gillespie Correspondence applied to two compatible and complete cotorsion pairs in X‚ąß\mathcal{X}^\wedge. These pairs can be regarded as examples of what we call cotorsion pairs relative to a thick subcategory of C\mathcal{C}. We establish some correspondences between Frobenius pairs, relative cotorsion pairs, exact model structures and Auslander-Buchweitz contexts. Finally, some applications of these results are given in the context of Gorenstein homological algebra by generalizing some existing model structures on the categories of modules over Gorenstein and Ding-Chen rings, and by encoding the stable module category of a ring as a certain homotopy category. We also present some connections with perfect cotorsion pairs, covering classes, and cotilting modules.Comment: 54 pages, 10 figures. The statement and proof of 2.6.21 was corrected. Typos corrected. Section 4 was improved, and new results in Section 5 were adde

    A geometrical view of scalar modulation instability in optical fibers

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    Full models of scalar modulation instability (MI) in optical fibers available in the literature usually involve complex formulations. In this paper, we present a novel approach to the analysis of MI in optical fibers by means of a simple geometrical description in the power vs. frequency plane. This formulation allows to relate the shape of the MI gain to any arbitrary dispersion profile of the medium, thus providing a simple insight. As a result, we derive a straightforward explanation of the non-trivial dependence of the cutoff power on high-order dispersion and derive explicitly the power that maximizes the gain. Our approach puts forth a tool to synthesize a desired MI gain with the potential application to a number of parametric-amplification and supercontinuum-generation devices whose initial-stage dynamics rely upon modulation instability.Fil: Hernandez, Santiago Martin. Comisi√≥n Nacional de Energ√≠a At√≥mica. Gerencia del √Ārea de Energ√≠a Nuclear. Instituto Balseiro; ArgentinaFil: Fierens, Pablo Ignacio. Instituto Tecnol√≥gico de Buenos Aires; ArgentinaFil: Bonetti, Juan Ignacio. Comisi√≥n Nacional de Energ√≠a At√≥mica. Gerencia del √Ārea de Energ√≠a Nuclear. Instituto Balseiro; ArgentinaFil: S√°nchez, Alfredo Daniel. Comisi√≥n Nacional de Energ√≠a At√≥mica. Gerencia del √Ārea de Energ√≠a Nuclear. Instituto Balseiro; ArgentinaFil: Grosz, Diego Fernando. Comisi√≥n Nacional de Energ√≠a At√≥mica. Gerencia del √Ārea de Energ√≠a Nuclear. Instituto Balseiro; Argentina. Instituto Tecnol√≥gico de Buenos Aires; Argentin

    Activation energy in particle suspensions

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    Assuming that the molar activation energy in a fluid is interpreted as a measure of the potential energy barrier required for the molecular movement [1], the viscosity of a fluid depends on the actual size of the molecules, and the presence of solid particles in a suspension increases the dissipation of energy when the system flows, therefore it is expected that the viscosity of the suspension is higher than that of the pure solvent at a given temperature. The dependence of the viscosity of some silica/glycol suspensions with the temperature can be fitted using an empirical function analogous to the Arrhenius equation, ln‚Ā°ő∑=E/RT-ln‚Ā°C, where ő∑ is the viscosity, C is a system-dependent constant, E is the molar activation energy for the viscous flow, T is the absolute temperature and R is the gas universal constant. When the temperature of the suspension decreases two effects are observed. First, larger aggregates of particles are formed due to the reduction of the thermal agitation and, second, the number of links among the molecules of the liquid phase increases. These two effects give place to a higher increase in the viscosity with the temperature compared to the pure solvent. Assuming that a higher viscosity value is due to a smaller free volume available for the molecular movement, and taking into account that the free suspension volume is limited only to the liquid fraction [2], it should be expected that the viscosity of the suspension is less sensitive to temperature than that of the pure solvent. In this work the dependence on the temperature of the viscosity values of the silica/glycol suspensions is compared to that of the liquid media. The results have shown a lower activation energy when the solid volume fraction increases, which has been explained with a scheme that assumes that the particle links are less sensitive to thermal energy absorption than the joining bonds among the solvent molecules. Our conclusion is that, for a given mechanical energy applied to the system, the thermal energy absorbed by the system is mainly used in the rupture of bonds between the solvent molecules. This study can be useful to understand the mechanisms that govern the differences in the activation energy values found between samples of foods, in which many factors are connected with sample composition [3]. [1] Briscoe B, Luckham P, Zhu S. Rheological properties of poly (ethylene oxide) aqueous solutions. J Appl Polym Sci 70 (1998) 419-429. [2] Shenoy AV. Rheology of filled polymer systems. Kluwer Acad Pub, 1999, The Netherlands. [3] Alvarez MD, Canet W. Time-independent and time-dependent rheological characterization of vegetable-based infant purees. J Food Eng 114 (2013) 449-464.Universidad de M√°laga, Campus de Excelencia Internacional Andaluc√≠a Tech

    The implementation of co-teaching and co-planning in the pre-selected environments of Sena’s technical and technological programs in Risaralda

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    El prop√≥sito de este proyecto es encontrar y crear una forma de implementar la adquisici√≥n del idiomaingl√©s en el Servicio Nacional de Aprendizaje (SENA). El SENA vela por invertir en el desarrollo social y t√©cnico de los trabajadores colombianos, ofreciendo y ejecutando una formaci√≥n profesional integral, para la incorporaci√≥n y desarrollo de las personas en actividades productivas que contribuyan al desarrollo social, econ√≥mico y tecnol√≥gico de este pa√≠s. As√≠, este proyecto de aula a trav√©s de actividades de co-planificaci√≥n y co-ense√Īanza buscar√° la implementaci√≥n de los niveles de competencia requeridos para cada programa espec√≠fico que ofrece la instituci√≥n. La finalidad de estasactividades y espacios radica en la poca efectividad que han tenido en las poblaciones objetivo las diferentes entidades encargadas de la ense√Īanza del idioma ingl√©s. Esperamos despertar el inter√©s delos estudiantes por el aprendizaje del ingl√©s como segundo idioma, y tambi√©n que entiendan este proyecto como un espacio de formaci√≥n de docentes para dar sus primeros pasos en el mundo profesional. As√≠ mismo, los encuentros entre ambas instituciones nos permitir√°n aplicar los conocimientos aprendidos durante el programa, pudiendo as√≠ generar un impacto positivo en el futuro de sus estudiantes.The purpose of this project is to find and create a way to implement the acquisition of the English language in the National Learning Service (SENA). SENA oversees investing in the social and technicaldevelopment of Colombian workers, offering and executing comprehensive professional training, for the incorporation and development of people in productive activities that contribute to the social, economic, and technological development of this country. Thus, this classroom project through co-planning and co- teaching activities will look for the implementation of the proficiency levels required for each specific program offered by the institution. The purpose of these activities and spaces lies in the lack of effectiveness that the different entities in charge of teaching the English language have had in the target populations. We hope to awaken an interest in the students for learning English as a second language, and also to understand this project as a space for developing teachers to have their first steps in the professionalworld. Likewise, the meetings between both institutions will allow us the application knowledge learned during the program, thus being able to generate a positive impact on the future of its students.PregradoLicenciado(a) en Biling√ľismo con √Čnfasis en Ingl√©sContent Acknowledgments 4 Justification 5 Objectives 8 Teaching objectives 8 Learning objectives 8 Conceptual Framework 9 Literature Review 16 Setting and Context 19 Participants 22 Needs of the institution 22 Instructional design 23 Expected results 24 Instruments 25 Lesson plan 25 Attachments/materials 31 Limitations 31 Implications 33 Professional Development Reflection 35 Professional Development Reflection part 1 35 Professional Development Reflection part 2 38 Conclusion 39 References 4
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