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The problem of the optimal placement and sizing of dynamic reactive power compensators in AC distribution networks is addressed in this paper from convex optimization. The exact mixed-integer nonlinear programming (MINLP) model is transformed into a mixed-integer second-order cone programming (MISOCP) model. The main advantage of the MISOCP formulation is the possibility of finding a global optimum with branch & cut combined with interior-point method due to the convex structure of the continuous part of the problem, i.e., the multi-period branch optimal power flow. The dynamic reactive power compensators are sized and dimensioned considering daily load curves and variable reactive power injections. Numerical validations are tested in the 33- and 69-bus test feeders using the CVX tool available for MATLAB with the MOSEK solver. These simulations demonstrate the effectiveness and robustness of the MISOCP approach when compared with the solution of the exact MINLP obtained in the GAMS software.

This paper presents the design, simulation, and implementation of an off-board charger of medium and low capacity batteries that incorporates a power factor corrector, reaches a low THD current with the advantage of providing higher robustness against network frequency variations, and allows the implementation of three different charging strategies. On the one hand, this charger consists of a galvanic isolation stage, followed by a bridge rectifier connected to a Boost converter, which regulates the power factor and THD. On the other hand, a Buck converter cascaded with the Boost serves as a current or voltage source, depending on the operating charging strategy. Subsequently, results obtained in the testing phase are presented, placing great emphasis on obtaining a power factor of 0.978 and a THD of 5.7%, which are compared to standard IEC 61000-3-2. Finally, the efficiency of the prototype, which reaches a maximum of 91.1%, is evaluated; conclusions are therefore presented., Este articulo presenta el diseño, simulación e implementación de un cargador off-board de baterías de mediana y baja capacidad que incorpora un corrector de factor de potencia, alcanza una baja distorsión armónica (THD) en corriente y permite la implementación de tres diferentes estrategias de carga. Este cargador está compuesto de una etapa de aislamiento galvánico, seguida por un puente rectificador el cual es conectado a un convertidor Boost quien regula el factor de potencia y el THD. Por otro lado, un convertidor Buck es conectado a la salida del convertidor Boost, actuando como una fuente de corriente o tensión, dependiendo de la estrategia de carga que se implemente. Posteriormente, se presentan los resultados haciendo énfasis en el valor de 0.978 para el factor de potencia y el de 5.7% para el THD, el cual es comparado con el estándar IEC 61000-3-2. Finalmente, se evalúa la eficiencia del prototipo encontrando un valor máximo de 91.1% y luego se presentan las conclusiones.

Disponer de suelo urbanizable es requisito indispensable para cumplir el propósito de brindar viviendas a la población, pero, el acceso a este suelo enfrenta obstáculos de tipo técnico, administrativo y normativo, que generan procesos caóticos de urbanización en las principales ciudades del país. En este artículo se analizan los instrumentos de gestión de suelo disponibles y utilizados en proyectos desarrollados por Metrovivienda en la localidad de Bosa en Bogotá D.C. Como resultado, se encuentra que las principales causas son: la escasez y los altos precios del suelo urbanizable y la persistencia del fenómeno de urbanización ilegal que pretende cubrir la demanda insatisfecha, especialmente para población no vinculada al mercado laboral formal. La Política Pública de Vivienda se enfoca principalmente en la asignación de subsidios a la demanda y la implementación de proyectos de construcción, pero, sin una Política Pública de Suelo que regule el uso y mercado, no se podrá planear a largo plazo y será muy difícil disminuir la brecha entre la oferta y la demanda de viviendas y lograr un desarrollo eficiente, equitativo y ordenado de la ciudad.

Xanthomonas axonopodis pv. manihotis (Xam) is the causal agent of bacterial blight of cassava, which is among the main components of human diet in Africa and South America. Current information about the molecular pathogenicity factors involved in the infection process of this organism is limited. Previous studies in other bacteria in this genus suggest that advanced draft genome sequences are valuable resources for molecular studies on their interaction with plants and could provide valuable tools for diagnostics and detection. Here we have generated the first manually annotated high-quality draft genome sequence of Xam strain CIO151. Its genomic structure is similar to that of other xanthomonads, especially Xanthomonas euvesicatoria and Xanthomonas citri pv. citri species. Several putative pathogenicity factors were identified, including type III effectors, cell wall-degrading enzymes and clusters encoding protein secretion systems. Specific characteristics in this genome include changes in the xanthomonadin cluster that could explain the lack of typical yellow color in all strains of this pathovar and the presence of 50 regions in the genome with atypical nucleotide composition. The genome sequence was used to predict and evaluate 22 variable number of tandem repeat (VNTR) loci that were subsequently demonstrated as polymorphic in representative Xam strains. Our results demonstrate that Xanthomonas axonopodis pv. manihotis strain CIO151 possesses ten clusters of pathogenicity factors conserved within the genus Xanthomonas. We report 126 genes that are potentially unique to Xam, as well as potential horizontal transfer events in the history of the genome. The relation of these regions with virulence and pathogenicity could explain several aspects of the biology of this pathogen, including its ability to colonize both vascular and non-vascular tissues of cassava plants. A set of 16 robust, polymorphic VNTR loci will be useful to develop a multi-locus VNTR analysis s