Sobretensiones por ferroresonancia en un sistema de distribución eléctrica rural: reporte de caso y simulación

The objective of this work was to analyze an overvoltage case in a rural distribution feeder belonging to an electrical distribution company in the southeast of the Buenos Aires Province in Argentina. The network was modeled in the Electromagnetic Transients Program, based on the electrical parameters that make up the circuit, in order to evaluate its behavior under various switching and load states. The simulation analysis showed that during certain operation and load situations, the conditions for the overvoltage phenomenon occurred, causing a voltage increase in the single-phase transformer feeding. The guidelines for prevention and control of the phenomenon were provided taking into account the results obtained in the study.El objetivo del trabajo presentado fue el de analizar un caso de sobretensión en un sistema de distribución de energía eléctrica rural (13,2kV) perteneciente a una Cooperativa de Electricidad del sudeste de la Policía de Buenos Aires, Rep. Argentina. A partir de los parámetros que componen el circuito eléctrico se modeló la red dentro del entorno del programa computacional Electromagnetic Transients Program, con el fin de evaluar su comportamiento ante distintas maniobras de interrupción y estados de carga. El análisis de la simulación demostró que, en ciertas situaciones de operación y carga, se conjugaron las condiciones para la ocurrencia del fenómeno de ferrorresonancia, ocasionando la elevación de tensión de alimentación en transformadores monofásicos. Considerando los resultados del estudio, se brindaron pautas a tener en cuenta para la prevención y control del fenómeno

Georreferenciación de las redes de distribución eléctrica con apoyo de imágenes de satélite y servicios de cartografía en la web / Georreferenciação de redes de distribuição eléctrica com apoio de imagens de satélite e serviço de mapeamento web

La georreferenciación es un neologismo que hace referencia a la posición con la que se define la ubicación de un objeto espacial (representado por punto, vector, área, volumen) en un sistema de coordenadas y datum determinado. A partir de la georreferenciación, es posible integrar diferentes fuentes de información utilizando como elemento en común la correspondencia geográfica. En este trabajo se presenta la experiencia del grupo de investigación LAT de la Universidad Nacional de Mar del Plata en la georreferenciación del sistema de distribución de energía eléctrica en zonas urbanas y rurales. Se describen los criterios que permitieron aprovechar los planos de las redes de media y baja tensión en una empresa distribuidora del sudeste de la provincia de Buenos Aires evitando la redigitalización de las mismas con el apoyo de imágenes satelitales y servicio de mapeo web como el Bing Map

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO

Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principle calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI. Supplemental material in the ancillary file

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis