Contribuciones desde la electroquímica para la optimización de materiales semiconductores con potencial uso en dispositivos fotovoltaicos”

Dr. Daniel Ramírez Ruiz Laboratorio de electroquímica y nanociencias Instituto de Química y Bioquímica, Facultad de Ciencias Universidad de Valparaíso. Av. Gran Bretaña 1111, Valparaíso. Se describe el trabajo histórico realizado por el grupo de electroquímica del Instituto de Química y Biquímica de la Facultad de Ciencias de la Universidad de Valparaíso, el cual se ha dedicado a la electrodeposición y caracterización de materiales semiconductors. Durante los últimos años, se ha podido dar un enfoque adicional al original, que es la intención de obtener dispositivos con aplicaciones útiles en el campo del aprovechamiento de la energía solar, por medio de la separación de agua para formar hidrógeno y, últimamente, por la conversion directa a energía eléctrica por medio de celdas fotovoltaicas. Como se podrá ver, la electroquímica puede jugar un rol fundamental en el desarrollo de este tipo de tecnologías ya que, un protocolo correcto de electrodeposición puede permitir ajustar parámetros relevantes para mejorar la eficiencia de dichos dispositivos. Como dicho desarrollo es aun incipiente en nuestro grupo, se han incluído también resultados de la literatura que demuestran con evidencias que esta ruta electroquímica es possible acoplarla a dispositivos útiles con estos fines.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Wrong Choices, Missed Chances: The Motivations of Opposition Politicians and the Ensuing Failures at Regime Change in Venezuela, 2013-2022

This work presents a study of the failures to achieve regime change in Venezuela between 2013 and 2022. By using the critical juncture framework, this thesis shows that there have been moments of opportunity where permissive conditions (i.e., structural factors) were present to achieve regime change, that the Venezuelan opposition was incapable of seizing upon those moments of opportunity because they made sub-optimum strategic and coordination choices, and that these choices were influenced by the motivations that opposition actors have to be in politics

Simulation of the fountain flow effect by means of the radial functions method (RFM)

1 CD-ROM : il.The purpose of this work is to simulate the fountain flow effect using a meshless technique (RFM) and, therefore, to explore the possibilities that the method offers for free surface problems. To the knowledge of the author, the fountain ow effect has not been simulated in the past by means of meshless techniques. In this thesis, a steady state was assumed for all simulations. This assumption is common in the literature and can be found for instance in [28, 27]. It originates from the consideration of a reference system that moves with the average velocity of the flow. For the flow in a slit, a power law model model with n varying between 0:6 and 1:1 was used to describe the variation of the viscosity with the shear rate. Another case considered in this thesis is the fountain flow of a Newtonian uid in an axisymmetric tube including the force of gravity. The organization of the thesis is as follows: Chapter 2 presents a brief overview of the literature corresponding to the simulation of the fountain flow effect. In Chapter 3, the Radial Functions Method is presented using the solution of the Poisson equation as an example. Chapter 4 deals with the implementation of the method to simulate the fountain flow effect; this entails the representation of the motion and continuity equations, and the appropriate boundary conditions (including the free boundary) in terms of Radial Basis Functions. The thesis ends with chapters corresponding to the conclusions derived from the simulations and a presentation of possible lines of research for future work.1 Introduction -- 2 Overview of the Literature -- 3 The Radial Functions Method (RFM)-- 4 Implementation and Results -- 4.1 Newtonian Case in a Slit -- 4.1.1 Modeling -- 4.1.2 Numerical Implementation -- 4.1.3 Results -- 4.2 Non-Newtonian Case in a Slit -- 4.2.1 Modeling and Numerical Implementation -- 4.3 Newtonian-Axisymmetric Case with Body Forces -- 4.3.1 Modeling and Numerical Implementation -- 4.3.2 Results --4.4 Fountain Flow E ect on Fiber Matrix Separation during Manufacturing of Short Fiber Filled Injection Parts -- 5 Conclusions -- 6 Future Work -- List of Figures -- List of Table

Evaluation and Influence of Recycled Concrete Aggregate Base Layers on Hma Pavement Performance

This research investigated the influence of the RCA base layers on the HMA pavement performance as compared with CA base layers using laboratory tests on collected base layer materials and field tests on corresponding pavement sections. Field and laboratory testing programs were conducted to investigate RCA and CA base layer materials in which identified test sections at the selected pavement sites were subjected to testing using FWD, walking profiler, and DCP. Visual distress surveys were also conducted at the selected pavement sections. RCA and CA base layer samples were collected from these pavement sites and were subjected to a laboratory testing program including: particle size analysis, Micro-Deval abrasion test, absorption, and specific gravity. Laboratory tests indicated that the investigated RCA base layer materials are in general “finer” than the CA base materials based on the FM and GN values. The RCA base layer materials also possessed higher absorption values compared with CA base materials. In terms of resistance to abrasion, Micro-Deval abrasion test results showed that RCA and CA base layer materials exhibited high mass loss, in general, compared with a mean mass loss of 15.05% for Wisconsin virgin coarse aggregates. Field tests evaluated the strength and modulus of the investigated RCA and CA base materials and pavement test sections based on DCP and FWD tests. The DCP test results indicated that the CBR and layer moduli values of both RCA and CA base layer types are comparable. The CBR and base layer modulus values obtained from the results of the DCP tests indicated in general good strength and modulus properties of the investigated RCA and CA bases. The FWD test results showed variability in pavement surface deflections within individual test sections and among the various pavement test sections. In general, less deflection D0 values exhibited by pavement test sections with RCA base layers compared with those with CA base layers. The back-calculated moduli for the RCA and CA base layers (EBase) exhibited significant variability within individual pavement test sections and among pavements. Comparison of the back-calculated layer moduli values Ebase for RCA and CA base layer pavement show that there are very high values exhibited by RCA base layers for example at STH 78, which could be attributed to the tufa formation. The results of the visual distress surveys and pavement profile measurements (in terms of calculated PCI and IRI) for investigated pavement test sections showed variability with classified pavement conditions ranging from poor to good. The HMA pavements with RCA base layers exhibited higher PCI values indicating better pavement quality. The HMA pavements with CA base layers exhibited lower IRI values compared with the HMA pavements with CA base layers indicating a smoother ride quality for HMA pavement with CA base layer