Clustering-based method for the feeder selection to improve the characteristics of load shedding

International audienceUnder-frequency load shedding (UFLS) schemes are designed by specifying a given amount of load to shed at various frequency thresholds to prevent the collapse of the electrical power system in the event of a large generation-load imbalance. An UFLS step is constituted of a group of medium-voltage feeders that trip when a given frequency threshold is reached. This study focuses on the method to be used when allocating a given feeder to a given step. First, the authors introduce performance metrics to quantify the accuracy level with which the UFLS target is met. Second, they model: the allocation method currently used in France; a variant of that method; and a new method introduced in this study, based on an automated clustering technique. Third, based on real consumption patterns measured from a vast area in France, and using the introduced performance metrics, they compare the efficiency of the three described methods. This study is conducted for the current state of loading of the considered distribution network and for a hypothetical situation with an increased share of distribution-side photovoltaic generation. For the chosen performance metrics, they demonstrate that the first two methods provide similar results while the clustering-based method performs remarkably better

Spectral properties in supersymmetric matrix models

We formulate a general sufficiency criterion for discreteness of the spectrum of both supersymmmetric and non-su-persymmetric theories with a fermionic contribution. This criterion allows an analysis of Hamiltonians in complete form rather than just their semiclassical limits. In such a framework we examine spectral properties of various (1+0) matrix models. We consider the BMN model of M-theory compactified on a maximally supersymmetric pp-wave background, different regularizations of the supermembrane with central charges and a non-supersymmetric model comprising a bound state of N D2 with m D0. While the first two examples have a purely discrete spectrum, the latter has a continuous spectrum with a lower end given in terms of the monopole charge.Comment: 40 pages, 5 figure

Study of an electronic steering antenna with a staggered phase shifter configuration

This paper presents a study of three possible solutions that can be taken into account to control the phase shift between elements in an antenna array. Because commercial digital phase shifters have become a strategic element by U.S. Government, these elements have increased their price. For this reason, it is necessary to adopt some solutions that allow us to deal with the design and construction of antenna arrays

Development of a Social Gamified Platform for e-Learning

The way in which nowadays education is evolving, makes it possible to associate it with MOOCs courses and gamification techniques to improve learning outcomes of students. To this end, this paper shows the development of an educational e-learning platform built upon the Elgg social framework, where a set of gamification elements were added: Points, achievements, leaderboards and rewards. For the future, effectiveness validations will be carried out with students as well as further developments with other types of gamification elements

Mobile Instant Messaging Apps: Usability Evaluation on iOS and Android Platforms and Recommendations for Developers

With the current growth in the use of smartphone devices, and the large amount of Mobile Instant Messaging applications available in the markets, this co-occurrence makes it highly valuable to evaluate the usability of this kind of applications in order to provide more satisfying user experiences. Within this paper, a systematic usability evaluation of Mobile Instant Messaging applications is presented, which will be applied to both iOS and Android platforms. Based on the results, it is suggested that this type of mobile applications present serious problems in performing tasks, poor user interfaces and lack of information about privacy and security features. Likewise, along with the results, this paper presents a list of usability recommendations to help developers improve their Instant Messaging applications

Thermal loads inside buildings with phase change materials: Experimental results

AbstractNowadays, European policies are promoting low energy buildings because of the high amount of energy consumption of the building sector. Phase change materials (PCM) have been studied in building implementation as a passive system to reduce the energy demand. Based in the experience obtained in the experimental set-up of Puigverd de Lleida (Spain), this paper pretends to analyze experimentally the PCM performance in a scenario with internal thermal gains. The experiments were done in three different cubicles with the same internal dimensions. The selection of the constructive systems used in these three cubicles allows the authors to evaluate the impact of using PCM in a typical Mediterranean building. A domestic heat pump for summer and an electric radiator for winter were installed to control the internal temperature of the cubicles. The results of summer period experiments show that the PCM cubicle stored the heat produced by the internal loads limiting the heat dissipation to the outer environment. Therefore, the energy consumed by the HVAC system of the PCM cubicle during the cooling period is higher than that of the other cubicles that dissipated the thermal loads according to the thermal resistance of their envelopes. Therefore, the PCM selection should take into account not only the comfort temperature but also the activity and functionality of the building

Red Multihaz de Desfase Escalonado para el Control de un Array de Antenas.

This paper presents a general systems that can be taken into account to control between elements in an antenna array. Because the digital phase shifter devices have become a strategic element and also some steps have been taken for their export by U.S. Government, this element has increased its price to the low supply in the market. Therefore, it is necessary to adopt some solutions that allow us to deal with the design and construction of antenna arrays. system based on a group of a staggered phase shift with external switching is shown, which is extrapolated array

ECG, an essential tool to guide arrhythmic mitral valve prolapse diagnosis

A 35-year-old man was referred for cardiac check-up because of suspected reflex syncope. He underwent a tilt-test challenge without syncope provocation. The electrocardiography (ECG) showed sinus rhythm with polymorphic premature ventricular contractions (PVC), with right bundle branch block morpholog

Efectos de la conducción eficiente en el tráfico y las emisiones mediante micro-simulación

[ES] El transporte por carretera es uno de los principales causantes de la emisión de gases de efecto invernadero y del deterioro de la calidad del aire en nuestras ciudades. Para atajar este problema las administraciones competentes están promoviendo diferentes medidas entre las que se encuentra el fomento de una conducción eficiente. La conducción eficiente comprende variadas recomendaciones para conseguir disminuir el consumo de combustible y las emisiones, entre las que se pueden citar conducir con marchas altas, evitar aceleraciones y frenadas bruscas o el mantenimiento de una distancia de seguridad suficiente para reaccionar suavemente a las variaciones del tráfico. Muchos estudios cifran los ahorros de combustible individuales entre el 5% y el 20%, pero apenas se encuentran investigaciones acerca de resultados globales según se incorporan más conductores eficientes al corredor o zona de estudio. En esta ponencia se describe el proceso de simulación de conducción eficiente para diferentes ratios de penetración entre los conductores. Para ello se parte de un análisis estadístico de perfiles de velocidad reales recogidos en ciertos itinerarios de Madrid, realizados primero con una conducción normal y posteriormente siguiendo las recomendaciones de un curso de conducción eficiente. A partir de este análisis se calibra el modelo de micro-simulación (Vissim), para posteriormente plantear diversos escenarios en función de la intensidad de tráfico y del porcentaje de conductores eficientes y calcular las emisiones mediante el modelo VERSIT+. Entre los problemas medioambientales más trascendentales para la sociedad, se encuentra el del cambio climático así como el de la calidad del aire en nuestras áreas metropolitanas. Los resultados muestran que los ahorros individuales son mayores en porcentaje que los ahorros globales. Incluso, en el escenario con mayor congestión, un mayor porcentaje de conductores eficiente provoca una mayor congestión y por tanto un aumento de las emisiones de CO2 y NOx.Garcia-Castro, A.; Monzon De Caceres, A. (2016). Efectos de la conducción eficiente en el tráfico y las emisiones mediante micro-simulación. En XII Congreso de ingeniería del transporte. 7, 8 y 9 de Junio, Valencia (España). Editorial Universitat Politècnica de València. 890-897. https://doi.org/10.4995/CIT2016.2015.3130OCS89089

On the design and measurement of a novel non-orthogonal multi-beam network for triangular arrays of three radiating elements

An innovative dissipative multi-beam network for triangular arrays of three radiating elements is proposed. This novel network provides three orthogonal beams in θ0 elevation angle and a fourth one in the broadside steering direction. The network is composed of 90º hybrid couplers and fixed phase shifters. In this paper, a relation between network components, radiating element distance and beam steering directions will be shown. Application of the proposed dissipative network to the triangular cells of three radiating elements that integrate the intelligent antenna GEODA will be exhibited. This system works at 1.7 GHz, it has a 60º single radiating element beamwidth and a distance between array elements of 0.57 λ. Both beam patterns, theoretical and simulated, obtained with the network will be depicted. Moreover, the whole system, dissipative network built with GEODA cell array, has been measured in the anechoic chamber of the Radiation Group of Technical University of Madrid, demonstrating expected performance