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Effect of population dynamics and land use on the contribution of sediments to reservoirs for hydropower generation
No full textSediment load in reservoirs causes loss of reservoir storage and reduces its usable life. There are management strategies focused in sediment removal or reducing trapping in reservoirs, and there are basin management strategies oriented to reduce sediment production and load reaching reservoirs. In a social and political moment, like the present time in Colombia, rural return migration is expected. Ex-ante evaluation of strategies to reducing sediment production is required, in order to implement them previously and avoid the acceleration of the reduction of the usable life of reservoirs. This paper presents the assessment of the impact on sediment production in a basin according to different land use planning strategies, in the context of the rural population dynamics expected in the coming years in Colombia. The San Carlos River basin contributes to a reservoir for hydropower generation, which currently generates the major percentage of hydropower energy in the power generation matrix of Colombia. We implemented on the basin the TETIS model, a distributed conceptual hydrological and sediment model. This model allows to estimate sediment production, through simulation of solid discharge series at anywhere in the basin. The TETIS sedimentological submodel was calibrated and validated using reservoir sedimentation volumes as an estimator of the total sediment transport. Different strategies and alternatives for land use were established, including lack of planning and agricultural policies. Results show an increase in the sediment production in the long term, if a policy on the adequate use of the soil is not implemented. The results allow to define the strategic zones of the basin where the efforts for the implementation of good agricultural practices, reforestation and soil conservation must be focused. © 2018 Oxford University Press. All rights reserved
Geothermal energy in Colombia as of 2018 [Energía geotérmica en Colombia hasta 2018]
No full textColombia is a country with great potential for the exploitation of geothermal energy due to its high volcanic activity caused by the subduction between the Nazca and South American tectonic plates. However, this energy is yet to be exploited. This article seeks to describe, by means of a literature review and information processing, the current status of geothermal energy in Colombia, including the current regulations, the limitations, the recommendations to develop the geothermal energy, and some of the most important projects, studies, and research papers that have been emerged on the discovery, exploration, and exploitation of geothermal energy within the country, emphasizing the areas where exploration projects have been initiated, such as the Nevado del Ruiz volcano, the Tufiño Chiles Cerro Negro volcanic system, the Azufral volcano geothermal area, and the Paipa geothermal area. Over the years, energy vulnerability in Colombia and a government policy of fostering sustainable development in different territories have generated favorable conditions for the exploitation of geothermal resources. Nevertheless, there are several technical, infrastructural, legal, and institutional barriers that slow the proper development of these projects. © 2020, Pontificia Universidad Javeriana. All rights reserved
Simulating current-energy converters: SNL-EFDC model development, verification, and parameter estimation
No full textIncreasing interest in power production from ocean, tidal, and river currents has led to significant efforts to maximize energy conversion through optimal design and siting and to minimize effects on the environment. Turbine-based, current-energy-converter (CEC) technologies remove energy from current-driven systems and in the process generate distinct wakes, which can interact with other CEC devices and can alter flow regimes, sediment dynamics, and water quality. This work introduces Sandia National Laboratories-Environmental Fluid Dynamics Code CEC module and verifies it against a two-dimensional analytical solution for power generation and hydrodynamic response of flow through a CEC tidal fence. With a two-dimensional model that accurately reflects an analytical solution, the effort was extended to three-dimensional models of three different laboratory-flume experiments that measured the impacts of CEC devices on flow. Both flow and turbulence model parameters were then calibrated against wake characteristics and turbulence measurements. This is the first time that turbulence parameter values have been specified for CEC devices. Measurements and simulations compare favorably and demonstrate the utility and accuracy of this numerical approach for simulating the impacts of CEC devices on the flow field. The model can be extended to future siting and analyses of CEC arrays in complex domains. © 2017 Elsevier Lt
SETMAT (Software engineering teaching method and theory): A theory of software engineering teaching [SETMAT (Software Engineering Teaching Method and Theory): Una teoría para la enseñanza de Ingeniería de Software]
No full textSoftware engineering (SE) teaching uses learning strategies to promote the acquisition of technical and social capabilities; typical strategies are project-based learning, collaborative learning, and problem-based learning. SE teachers need to compare, evaluate, and select strategies and practices for specific courses, but they are usually described in imprecise and subjective manners. This paper describes SETMAT (Software Engineering Teaching Method and Theory), a descriptive theory of SE teaching with a common conceptual framework for describing teaching strategies and practices, combining concepts and relationships of SE. SETMAT has been used in a pilot study by teachers of Colombia, Chile, and Mexico to represent their SE teaching practices. SETMAT adoption would allow to represent, compare, compose and transfer SE teaching practices and strategies. © 2019, Associacao Iberica de Sistemas e Tecnologias de Informacao. All rights reserved
Characterization of the political system in colombia. Instable structure, restrictive/stable process and poor political results [Caracterización del sistema político colombiano. Estructura inestable, proceso restrictivo/estable y resultados políticos bajos]
No full textIn this article, a characterization of the political system in Colombia is presented, based on three political dimensions (structure, process and political result), with the purpose of showing that the creation of the Colombian state plays a decisive role in the configuration and performance of its political regime. Although it is argued that this regime is and has been democratic during most part of its existence, a significant paradox can be found inside the system: The presence of an unstable political structure, a restrictive political process and low levels of satisfaction in fundamental functions of the State, but even so, it can be considered a stable political system, comparatively speaking. © 2018, Universidad del Zulia. All rights reserved
A brief discussion of the magnetocaloric effect in thin films of manganite doped with chromium
No full textIn this work we report on the magnetocaloric effect of La2/3Ca1/3MnO3 (LCMO) and La2/3Ca1/3Mn0.94Cr0.06O3 (LCMCrO) manganite thin films grown by DC magnetron sputtering on LaAlO3 (100) substrates. X-ray diffraction shows that both doped and undoped films crystallize in the orthorhombic structure. Magnetic measurements show a decrease in both the Curie temperature, TC , and the saturation magnetization, MS , for the LCMCrO sample. The change in the magnetic entropy (?Sm ) was extracted from hysteresis loops at different temperatures around the ferromagnetic to paramagnetic transition, displaying a maximum of entropy change (?Sm ) max near TC in both films. Moreover, a shift in (?Sm ) max toward temperatures above TC with increasing magnetic field and a broadening of the entropy change curve were observed. Results of refrigeration cooling power show a lower efficiency for LCMCrO. In order to obtain a local insight into the magnetic interactions of these films, measurements of X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) were performed. XMCD suggests that an antiferromagnetic coupling between Mn4+ - Mn3+ is favored with Cr3+ incorporation, which reduces the Mn L 2,3 XMCD signal and results in a decrease of MS and (?Sm ) max in LCMCrO films. © Published under licence by IOP Publishing Ltd
Response of mid-rise reinforced concrete frame buildings to the 2017 Puebla earthquake
No full textThe response of mid-rise reinforced concrete (RC) buildings in Mexico City after the 2017 Puebla Earthquake is assessed through combined field and computational investigation. The Mw 7.1 earthquake damaged more than 500 buildings where most of them are classified as mid-rise RC frames with infill walls. A multinational team from Colombia, Mexico, and the United States was rapidly deployed within a week of the occurrence of the event to investigate the structural and nonstructural damage levels of over 60 RC buildings with 2 12 stories. The results of the study confirmed that older mid-rise structures with limited ductility capacity may have been shaken past their capacity. To elucidate the widespread damage in mid-rise RC framed structures, the post-earthquake reconnaissance effort is complemented with inelastic modeling and simulation of several representative RC framing systems with and without masonry infill walls. It was confirmed that the addition of non-isolated masonry infills significantly impacts the ductility capacity and increases the potential for a soft-story mechanism formation in RC frames originally analyzed and designed to be bare systems. © 2019, Earthquake Engineering Research Institut
Tunable band structure in 2D Bravais–Moiré photonic crystal lattices
No full textThis work introduces the recent so called Bravais Moiré theory in the context of two dimensional photonic crystals. In particular, new periodic cells involving commensurable bilayer rotated square alignments of photonic crystals with different permittivity constants are considered. The corresponding band gaps are wider than those usually reported in literature for square lattice dielectric structures, and a practical comparison is carried out in the calculation in order to verify such assert. These photonic gaps can be adjusted by changing different lattice parameters, such as the commensurable angle, and the permittivities involved. © 2019 Elsevier B.V
Crisp-dm/smes: A data analytics methodology for non-profit smes
No full textThe exponential increase in information due to technological advances and the development of communications has created the need to make decisions based on the data analysis. This trend has opened the doors to new approaches to data understanding and decision-making. On the one hand, companies need to follow data analytic methodologies to manage large volumes of information with big data tools. On the other hand, there are non-profit small and medium-sized enterprises (SMEs) that make efforts to address data analytics according to their different sources and types. They find challenges such as lack of knowledge in methodological and software tools, which allow timely deployment for decision-making. In this paper, we propose a data analytics methodology for non-profit SMEs. The design of this methodology is based on CRISP-DM as a reference framework, is represented by Software Process Engineering Metamodel (SPEM) and is characterized by being simple, flexible, and low implementation costs. © Springer Nature Singapore Pte Ltd. 2020
Assessing Colombia's policy of socio-economic stratification: An intra-city study of self-reported quality of life
No full textThis paper aims to analyse whether the Colombian government's classification of households into socio-economic strata accurately reflects the level of quality of life of households in Medellin. To this end, logit multilevel models and a novel graphic analysis were used. Our findings suggest that the stratification criteria currently used in Medellin should be revised. The socio-economic strata, which only considers the characteristics of the dwellings, streets and surrounding areas, explain approximately one tenth of the variability in self-reported quality of life. When other economic and non-economic factors are considered, a different strata ranking for guiding public policies than that used in Medellin was estimated. Neighbourhood safety and personal safety are key drivers of quality of life, whereas higher consumption expenditure is most effective in the most disadvantaged strata. © 2019 Elsevier Lt