Start-up of virtual synchronous machine: methods and experimental comparison

A modern grid is smarter mainly in the advance in information and communication technologies, while the power processing mechanism does not make a big difference. To make a modern grid smarter, the grid control should be improved to process the power in a smarter way. Therefore, it is easily foreseen that virtual synchronous machines, which emulates the synchronous machines based on power converters, may have big potentials in a future energy internet. This paper uses the Synchronous Power Controller with emulated and improved synchronous machine characteristics for renewable generation systems and proposes two start-up strategies. The proposed strategies are explained in detail, verified and compared by experimental results.Peer ReviewedPostprint (published version

El acceso a la condición de funcionario de la unión europea mediante oposición general. Estudio de caso.

El presente Trabajo Fin de Grado trata del reclutamiento de los funcionarios de las Instituciones de la Unión Europea. Se contiene en el mismo una exposición de los preceptos del Estatuto de los Funcionarios que regulan dicho reclutamiento, así como las Normas Generales por las que se rigen las oposiciones generales, que constituyen una modalidad de procedimiento de concurso para seleccionar a los candidatos que acceden a la condición de funcionarios. Utilizando una reciente convocatoria de oposición general para seleccionar candidatos para cubrir puestos funcionarios de Administradores (AD 5), se exponen las distintas fases de este procedimiento de selección, los problemas surgidos en la aplicación de las normas por las que se regula y la jurisprudencia aparecida para resolver los mismos.This essay is about the recruitment of civil servants for the diferent institutions of the European Union. It contains a statement of the provisions of the Staff Regulations governing such recruitment, as well as the General Rules governing open competitions, which are a form of competitive process to select candidates who access civil servant status. Using a recent call for open competition to select candidates to fill staff Administrators (AD 5), the various stages of this selection procedure and the different types of problems appeared in the application of the rules by which is regulated are discussed, as well as the case-law developed to solve them

Multi-objective metaheuristics for multi-disciplinary engineering applications

Editorial. Special Issue: Multi-objective metaheuristics for multi-disciplinary engineering applicationsPublicad

.NET Operator SDK Developing Kubernetes Operators in .NET

Kubernetes, microservices architectures and cloud computing are rising trends in the soft ware industry. Ever growing enterprises required more and more attributes such as avail ability, maintainability, security and reliability. They are turning to technologies that enable these and riding the wave is Kubernetes. Kubernetes aims to automate a lot of operational knowledge but does it know how to automate domain-specific operational tasks? To solve this problem there are several projects to develop these Kubernetes-native domain aware applications called Operators. The problem is that these are mostly developed in Go for Go developers and there are none to develop using .NET. .NET is used worldwide across enterprises which makes it an interesting choice as the tech nology in which to build Operators. Enterprises should be allowed to keep consistency across their technologies of choice instead of implementing an Operator in a language they might not be familiar with or not be allowed by their clients. To solve this problem the .NET Operator SDK was created. This document presents the current state of the .NET Operator SDK which is of a MVP. With the .NET Operator SDK developers will be able to develop Operators in .NET more easily than they would using a simple client. It reduces a lot the boilerplate code and offers a baseline structure for developers to build onto. Having a more structured codebase will allow to build more complex Operators to address complex business needs

A New Protocol Using Artificial Seeds to Evaluate Dietary Preferences of Harvester Ants in Semi-arid Environments

The preferences of seed intake by harvester ants (Pogonomyrmex spp.) have been debated for a long time, mainly due the lack of repeatable methods to draw clear conclusions. However, several characteristics of the food resource are well recognized as the drivers of such selective predation. For instance, resource quality (i.e., availability of carbohydrates, lipids, and proteins) is one factor that could explain the observed foraging patterns of Pogonomyrmex species. In this sense, experimental approaches using artificial resources (e.g., synthetic seeds/diaspores) have provided an useful and alternative tool to study ant’s food foraging behavior. Therefore, it is expected that the use of artificial seeds also could offer a versatile way to assess the influence of resource quality exert on the resource selection by harvester ants. On the other hand, empirical experiments involving harvester ants and artificial seeds are still rare in the literature and it is not known if such methodology is efficient with different Pogonomyrmex species. In this study carried out in a Neotropical arid environment of central Mexico, we tested a simple but fundamental question: Do harvester ants (Pogonomyrmex barbatus) predate artificial seeds with manipulated nutrient content (lipids and proteins) in the field? We found that the proportion of native seeds removed was lower than the proportion of artificial seeds removed. However, we found no difference between the removal of artificial seeds containing only lipids and the seeds containing lipids + proteins. These findings indicate that the artificial seeds synthesized by us could be an effective method to test different ecological hypothesis involving harvester ants. Moreover, our empirical experiment offers a benchmark to study the influence of resource quality on the food foraging behavior of harvester ants in Neotropical arid environments

Implementing an Android Tool for Visually Impaired Students of E-Learning

This article aims to describe the process of learning and development of an educational tool designed for mobile devices (smartphones) with Android technology. In summary, the application was developed based on the virtual learning environment Moodle and aims to develop a learning environment that supports the visually impaired students of e-learning, allowing them to ask questions, discuss and share ideas through forums and use chat rooms in real time. The fundamental purpose of this application is to cooperate with scientific knowledge in the sense that this is a representation of technological advance on the accessibility tools in distance education mode and provide comfort, flexibility and accessibility for the visually impaired students, realizing that education should always be inclusive

Multi-terminal HVDC grids with inertia mimicry capability

The high-voltage multi-terminal dc (MTDC) systems are foreseen to experience an important development in the next years. Currently, they have appeared to be a prevailing technical and economical solution for harvesting offshore wind energy. In this study, inertia mimicry capability is added to a voltage-source converter-HVDC grid-side station in an MTDC grid connected to a weak ac grid, which can have low inertia or even operate as an islanded grid. The presented inertia mimicry control is integrated in the generalised voltage droop strategy implemented at the primary level of a two-layer hierarchical control structure of the MTDC grid to provide higher flexibility, and thus controllability to the network. Besides, complete control framework from the operational point of view is developed to integrate the low-level control of the converter stations in the supervisory control centre of the MTDC grid. A scaled laboratory test results considering the international council on large electric systems (CIGRE) B4 MTDC grid demonstrate the good performance of the converter station when it is connected to a weak islanded ac grid.Peer ReviewedPostprint (author's final draft

Realization of a 10 kW MES power to methane plant based on unified AC/DC converter

This paper presents a galvanic isolated multi output AC/DC topology that is suitable for Microbial electrosynthesis (MES) based Power to Methane energy storage systems. The presented scheme utilizes a three phase back to back converters, a single-input and multiple-output three phase transformer, single diode rectifiers and buck converters that employ a proper interconnection between MES cells and the mains. The proposed topology merges all the required single phase AC/DC converters as a unified converter which reduces the overall system size and provides system integrity and overall controllability. The proposed control scheme allows to achieve the following desired goals:1) Simultaneous control of all cells; 2) Absorbing power from the grid and covert to methane when the electricity price goes down; 3) the power factor and the quality of grid current is under control; 4) Supplying MES cells at the optimal operating point. For verification of system performance, Real time simulation results that are obtained from a 10-kW MES energy storage are presented.Postprint (author's final draft

Dynamics estimation and generalized tuning of stationary frame current controller for grid-tied power converters

The integration of AC-DC power converters to manage the connection of generation to the grid has increased exponentially over the last years. PV or wind generation plants are one of the main applications showing this trend. High power converters are increasingly installed for integrating the renewables in a larger scale. The control design for these converters becomes more challenging due to the reduced control bandwidth and increased complexity in the grid connection filter. A generalized and optimized control tuning approach for converters becomes more favored. This paper proposes an algorithm for estimating the dynamic performance of the stationary frame current controllers, and based on it a generalized and optimized tuning approach is developed. The experience-based specifications of the tuning inputs are not necessary through the tuning approach. Simulation and experimental results in different scenarios are shown to evaluate the proposal.Peer ReviewedPostprint (published version

Novel achievements with an old metal: Copper-promoted synthesis of four-membered azacycles

The synthesis of four-membered azacycles is of importance because of the chemical and biological relevance of these compounds. Recent progress in copper-catalyzed reactions has been applicable to a variety of research fields, such as heterocyclic synthesis. The aim of the current review is to summarize the synthesis of strained four-membered ring taking advantage of copper catalyzed and mediated processes. © 2014 The Royal Society of Chemistry.Peer Reviewe