Efficient Day-Ahead Dispatch of Photovoltaic Sources in Monopolar DC Networks via an Iterative Convex Approximation

The objective of this research is to propose an efficient energy management system for photovoltaic (PV) generation units connected to monopolar DC distribution networks via convex optimization while considering a day-ahead dispatch operation scenario. A convex approximation is used which is based on linearization via Taylor’s series expansion to the hyperbolic relations between voltages and powers in the demand nodes. A recursive solution methodology is introduced via sequential convex programming to minimize the errors introduced by the linear approximation in the power balance constraints. Numerical results in the DC version of the IEEE 33-bus grid demonstrate the effectiveness of the proposed convex model when compared to different combinatorial optimization methods, with the main advantage that the optimal global solution is found thanks to the convexity of the solution space and the reduction of the error via an iterative solution approach. Different objective functions are analyzed to validate the effectiveness of the proposed iterative convex methodology (ICM), which corresponds to technical (energy losses reduction), economic (energy purchasing and maintenance costs), and environmental (equivalent emissions of CO (Formula presented.) to the atmosphere in conventional sources) factors. The proposed ICM finds reductions of about (Formula presented.) in daily energy losses, (Formula presented.) in energy purchasing and operating costs, and (Formula presented.) in CO (Formula presented.) emissions when compared to the benchmark case in the DC version of the IEEE 33-bus grid. All numerical validations were carried out in the MATLAB programming environment using the SEDUMI and SDPT3 tools for convex programming and our own scripts for metaheuristic methods. © 2023 by the authors

Sincronía biológica entre cuatro especies de Anastrepha y sus hospederos Altos de Pacora - Panamá 1995-1996

En Altos de Pacora, ubicada al este de Panamá, se analizó la sincronía en la ocurrencia de Anastrepha en relación a tres especies de plantas hospederas. De Pouteria buenaventurensis cuya maduración coincide con el incremento en la precipitación, emergieron Anastrepha intermedia n, sp., de la semilla y Anastrepha serpentina, de la pulpa; de Pouteria sp. cuya fructificación coincide con la máxima precipitación, emergieron Anastrepha leptozona de semilla y de pulpa Anastrepha serpentina, de Duguetia panamensis donde la maduración se da al declinar la precipitación, emergió Anastrepha colombiana n. sp., que se alimenta de pulpa A. intermedia n. sp, presentó mayor infestación en junio y julio, variando de 30 a 54% con una intensidad de infestación promedio para 1995 de 3.73 larvas/fruto. La emergencia de adultos criados fue superior a finales de junio y las mayores capturas en trampas ocurrieron en julio, agosto y septiembre. El porcentaje de infestación en A. serpentina fue superior en agosto y la primera quincena de septiembre variando de 63 a 83%, la intensidad de infestación para esta especie varió de 5.3 a 11.2 larvas/fruto; la emergencia de adultos criados fue mayor en julio e inicios de septiembre y solo hubo capturas en trampa entre junio y julio. Para A. leptozona la infestación varió de 8 a 41% y la intensidad de infestación entre 1 y 8 larvas/fruto, la emergencia de adultos criados fue superior a finales de agosto y solo se capturó a principio de junio. La infestación de A. serpentina en Pouteria sp, varió de 11 a 73% y la intensidad de infestación de 3.6 a 14.6 el mayor número de adultos criados ocurrió a finales de agosto y los adultos se capturaron en trampas entre junio y julio. La infestación de A. colombiana varió de 8 al 100% en tanto que la intensidad de infestación fluctuó entre 3 y 11.4 larvas/fruto. La ocurrencia de adultos fue superior en junio y las capturas con trampas fueron más frecuentes en el período seco

Identities of Choi-Lee-Srivastava involving the Euler-Mascheroni’s constant

We give an elementary deduction of the Choi-Lee-Srivastava’s identities involving the Euler Mascheroni’s constant, thus from them is immediate the identity of Wilf

Co-evolutionnary network approach to cultural dynamics controlled by intolerance

Starting from Axelrod's model of cultural dissemination, we introduce a rewiring probability, enabling agents to cut the links with their unfriendly neighbors if their cultural similarity is below a tolerance parameter. For low values of tolerance, rewiring promotes the convergence to a frozen monocultural state. However, intermediate tolerance values prevent rewiring once the network is fragmented, resulting in a multicultural society even for values of initial cultural diversity in which the original Axelrod model reaches globalization

Population genetics of self-incompatibility in a clade of relict cliff-dwelling plant species

The mating systems of species in small or fragmented populations impact upon their persistence. Small self-incompatible (SI) populations risk losing S allele diversity, responsible for the SI response, by drift thereby limiting mate availability and leading to population decline or SI system breakdown. But populations of relict and/or endemic species have resisted these demographic conditions over long periods suggesting their mating systems have adapted. To address a lack of empirical data on this topic, we studied the SI systems of three relict cliff-dwelling species of Sonchus section Pustulati (Asteraceae): S. masguindalii, S. fragilis and S. pustulatus in the western Mediterranean region. We performed controlled pollinations within and between individuals to measure index of SI (ISI) expression and identify S alleles in multiple population samples. Sonchus masguindalii and S. pustulatus showed strong SI (ISI = 0.6–1.0) compared to S. fragilis (ISI = 0.1–0.7). Just five S alleles were estimated for Spanish S. pustulatus and a moderate 11-15 S alleles for Moroccan S. pustulatus and S. fragilis, respectively. The fact that autonomous fruit set was generally improved by active self-pollination in self-compatible S. fragilis suggests that individuals with weak SI can show a wide range of outcrossing levels dependent on the degree of self or outcross pollen that pollinators bear. We conclude that frequent S allele dominance interactions that mask the incompatibility interactions of recessive S alleles leading to higher mate availability and partial breakdown of SI leading to mixed mating, both contribute to reproductive resilience in this group.Ministerio de Ciencia e Innovación (España) BES–2007–17066 CGL2010–16512 CGL2006–0081

Propiedades de las rocas volcánicas de Canarias (España) utilizadas como material de escollera

In the Canary Islands, there is a wide spectrum of volcanic rocks with different properties to be used in public works. The aim of this study is to analyse the physical-mechanical properties of all the volcanic rocks present in the Canary Island archipelago in order to determine their suitability for use in maritime construction works. The great variety of volcanic rocks present on the islands have been grouped into lithotypes based on similar geo-mechanical behaviour. The laboratory test results obtained for these lithotypes establish their suitability or not to be used as breakwater material in accordance with Spanish regulations.En el archipiélago canario existe un amplio espectro de rocas volcánicas con diferentes propiedades para ser utilizadas en obras públicas. El objetivo de este estudio es analizar las propiedades físico-mecánicas de todas las rocas volcánicas presentes en el archipiélago canario con el fin de determinar su idoneidad para ser utilizadas en obras de construcción marítima. La gran variedad de rocas volcánicas presentes en las islas, se han agrupado en litotipos basados en un comportamiento geomecánico similar. Los resultados de los ensayos de laboratorio obtenidos para estos litotipos establecen su idoneidad o no para ser utilizados como material de escollera de acuerdo con la normativa española