Low computational cost method to calculate the hosting capacity in radial low voltage networks

This study presents a low computational cost method to compute the hosting capacity of each user in a radial single phase power network. It is assumed every user install generation. The method is based on two key points, one is the Thevenin equivalent for the installation of each user and for the whole system, the other is the representation of the operation region through the contour of the regions for the Thevenin circuits parameters. The method calculates the range of power injection allowed for each user in order to comply with the network and devices constraints. This range can be included in optimization problems to define the feasible operation region avoiding the explicit inclusion of the power flow equations. The method is illustrated on a simple case study with three users.Ministerior de Economía y Competitividad. Proyecto ENE2016-80638-R Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

An experimental and modelling exploration of the host-sanction hypothesis in legume-rhizobia mutualism

Despite the importance of mutualism as a key ecological process, its persistence in nature is difficult to explain since the existence of exploitative, 'cheating' partners that could erode the interaction is common. By analogy with the proposed policing strategy stabilizing intraspecific cooperation, host sanctions against non N2 fixing, cheating symbionts have been proposed as a force stabilizing mutualism in legume-Rhizobium symbiosis. Following this proposal, penalizations would include decreased nodular rhizobial viability and/or early nodule senescence in nodules occupied by cheating rhizobia. In this work, we analyze the stability of Rhizobium-legume symbiosis when "cheating" strains are present, using an experimental and modelling approach. We used split-root experiments with soybean plants inoculated with two rhizobial strains, a cooperative, normal N2 fixing strain and an isogenic non-fixing, “perfect” cheating mutant derivative that lacks nitrogenase activity but has the same nodulation abilities inoculated to split-root plants. We found no experimental evidence of functioning plant host sanctions to cheater rhizobia based on nodular rhizobia viability and nodule senescence and maturity molecular markers. Based on these experiments, we developed a population dynamic model with and without the inclusion of plant host sanctions. We show that plant populations persist in spite of the presence of cheating rhizobia without the need of incorporating any sanction against the cheater populations in the model, under the realistic assumption that plants can at least get some amount of fixed N2 from the effectively mutualistic rhizobia occupying some nodules. Inclusion of plant sanctions merely reduces the time needed for reaching plant population equilibrium and leads to the unrealistic effect of ultimate extinction of cheater strains in soil. Our simulation results are in agreement with increasing experimental evidence and theoretical work showing that mutualisms can persist or even improve in presence of cheating partners

DNA extraction from leaves of Vaccinium cylindraceum SMITH (Ericaceae). The use of RAPD markers to detect genetic variation. Preliminary results.

Vaccinium cylindraceum Smith is an endemic Ericaceae from Azores archipelago. This species is being produced by seed germination, micropropagation and stem cuttings. The produced plants are then reintroduced in their natural but disturbed environment and used to repopulate protected areas meanwhile infested with more or less invasive exotic flora. In order to protect the genetic variability within the species, a study of genetic variation between and within populations from different islands was started. DNA extraction was achieved on fresh, dried and criopreserved leaves and the First results using the PCR technique are also presented

Unit Commitment with Load Uncertainty by Joint Chance-Constrained Programming

This paper presents an algorithm to solve a unit commitment problem that takes into account the uncertainty in the demand. This uncertainty is included in the optimization problem as a joint chance constraint that bounds the minimum value of the probability to jointly meet the deterministic power balance constraints. The demand is modeled as a multivariate, normally distributed, random variable and the correlation among different time periods is also considered. A deterministic mixed-integer linear programming problem is sequentially solved until it converges to the solution of the chanceconstrained optimization problem. Different approaches are presented to update the z-value used to transform the joint chance constraint into a set of deterministic constraints. Results from a realistic size case study are presented and the values obtained for the multivariate normal distribution probability are compared with the ones obtained by using a Monte Carlo simulation procedureUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Editorial

sin resume

Aprendizaje de la programación guiado por los errores de compilación

Los errores de programación y en concreto los de tiempo de compilación siempre han sido un área de interés en el campo de la enseñanza de la programación. Esto lo demuestran los distintos artículos que aparecen periódicamente en congresos de docencia de la informática, tanto nacionales como internacionales. Estos estudios se basan en la relación entre errores de programación y carencias conceptuales o malas prácticas de programación, y orientar a los docentes en las áreas y conceptos de programación que se tendrían que reforzar en la enseñanza de la programación. Sin embargo, estos estudios se realizan siempre fuera del proceso de aprendizaje de los estudiantes, con lo cual sólo se extraen conclusiones generales para posteriores cursos y sin poder proporcionar una realimentación real e individualizada a los alumnos. Hemos creado un sistema, denominado COLMENA que se integra con el entorno de desarrollo integrado para recopilar información sobre el análisis estático, errores de compilación y warnings, que los estudiantes generan durante un ejercicio de programación. Además, esta información sobre errores se visualiza a los usuarios clasificada por familias de errores, sesiones de prácticas y alumnos. Permitiendo al profesor realizar un seguimiento completamente personalizado, para un grupo o un alumno concreto. Por otra parte, facilita la documentación de los distintos errores, estableciendo una relación de estos con los conceptos de programación y buenas prácticas relacionadas. Además, permite a los alumnos darse cuenta de los errores que cometen con más frecuencia y reforzar el conocimiento de estos. A través de esta herramienta, por tanto, se consigue un flujo de intercambio de información que puede ayudar a profesores y alumnos en la mejora del proceso enseñanza-aprendizaje, y así perfeccionar explícitamente detalles sobre pautas de programación o conceptos relativos a la misma que antes no se apreciaban o conocer la evolución de los errores de un grupo a lo largo de una asignatura.SUMMARY -- Studies on errors in programming activities have always been considered relevant among scientific communities. Thus, different approaches are explored every year in national and international conferences about programming teaching and learning. All of these studies deal with the relationship between programming errors and bad habits in programming, in order to generate guidance for teachers in concepts where their students fail. However, these kinds of studies are conducted outside the students' natural programming process, which prevents teachers from receiving a feedback report in real-time. We have created an eclipse plug-in, called COLMENA, whose purpose is to recover compilation errors and warnings generated by the students during programming lessons. Moreover, this information is displayed in a specific portal where students can retrieve information about the errors, their solutions and different reports about individual and collective information, such as specific groups or sessions inside a subject. Students have the possibility to learn about the solution to their most common errors in the system or their top-10 error list. Through COLMENA, we aim to assist teachers and students with programming tips and ideas that generate less errors and improve the teacher-learning process. This kind of information, previously discarded, allows us to gain a new perspective about the problems that users have in a specific practical lesson or in a whole subject

Individualized exercises for continuous assessment in engineering

This project focuses on the development of a web application that automatically grades the solution to engineering exercises. The input data of each exercise is different for each student in order to reduce plagiarism and increase motivation. Students can access the web app from any device with internet access (computer, laptop, phone, …) at any time. The fact that the exercises are enunciated and evaluated in an individualized way eliminates the possibility for students to share the solutions and divert the profitable collaboration between students towards the learning of the resolution procedure itself. From the professor’s perspective, this tool allows an efficient and continuous evaluation of students. Besides, the storage of the data (number of attempts, time required, etc.) provides valuable information both for the self-assessment of the professor and for the analysis of the individualized learning process of each student. The web application is coded in Python, which easily allows the incorporation of additional features according to the needs of professors and students. The web application has already been tested during two academic years in two Spanish universities and for several engineering degrees. Ten professor and more than 2000 students have already benefit from this web application.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Una asignatura de algoritmos, convergencia metodológica hacia el EEES

¿Qué puede hacer un profesor que imparte una asignatura cuyos contenidos no son triviales, que los estudiantes ya tienen catalogada como asignatura difícil, que tiene más de trescientos alumnos divididos en tres grupos de teoría y que tienen unos niveles de rendimiento de los alumnos muy bajo? En el congreso Jenui 2003 Miguel Valero realizó una conferencia titulada "¿Qué tienen que ver los créditos ECTS con el Tour de Francia?" [6] en el que hacía una analogía entre el Tour de Francia y las asignaturas dentro del Espacio Europeo de Educación Superior (EEES). Los planteamientos del EEES ofrecen ideas pedagógicas muy valiosas; pero hasta que no se aplican es difícil comprobar sus resultados, sobre todo en contextos difíciles como el descrito. En este artículo pretendemos describir la experiencia en la aplicación de estos planteamientos en el caso concreto de una asignatura de algoritmos [2] de una titulación de Ingeniería Técnica en Informática

Decontamination of Diesel particles from air by using the Counterfog (R) system

The existence of particles with diameter under 10m in air is strongly correlated with respiratory diseases. These particles are profusely produced by heating systems, traffic, and Diesel engines creating a serious problem to modern cities. Natural mechanisms removing particles from the atmosphere are too slow to deal with the huge amount of particles daily released by human activity. The objective of this work is to measure the effectiveness of a new technology called Counterfog (R) to eliminate airborne particles. The results show that Counterfog (R) is able to wash out PM10, PM5, and PM2.5 Diesel-generated airborne particles quite efficiently.This work has been funded by the FP7-SEC-2012-1 program of the EU Commission under grant number 312804