Auto-tuning Distributed Stream Processing Systems using Reinforcement Learning

Fine tuning distributed systems is considered to be a craftsmanship, relying on intuition and experience. This becomes even more challenging when the systems need to react in near real time, as streaming engines have to do to maintain pre-agreed service quality metrics. In this article, we present an automated approach that builds on a combination of supervised and reinforcement learning methods to recommend the most appropriate lever configurations based on previous load. With this, streaming engines can be automatically tuned without requiring a human to determine the right way and proper time to deploy them. This opens the door to new configurations that are not being applied today since the complexity of managing these systems has surpassed the abilities of human experts. We show how reinforcement learning systems can find substantially better configurations in less time than their human counterparts and adapt to changing workloads

The use of geographic information systems for the optimal location of biomass power plants in the Madrid Community (Spain)

This article has been extracted from the results of a thesis entitled “Potential bioelectricity production of the Madrid Community Agricultural Regions based on rye and triticale biomass.” The aim was, first, to quantify the potential of rye (Secale Cereale L.) and triticale ( Triticosecale Aestivum L.) biomass in each of the Madrid Community agricultural regions, and second, to locate the most suitable areas for the installation of power plants using biomass. At least 17,339.9 t d.m. of rye and triticale would be required to satisfy the biomass needs of a 2.2 MW power plant, (considering an efficiency of 21.5%, 8,000 expected operating hours/year and a biomass LCP of 4,060 kcal/kg for both crops), and 2,577 ha would be used (which represent 2.79% of the Madrid Community fallow dry land surface). Biomass yields that could be achieved in Madrid Community using 50% of the fallow dry land surface (46,150 ha representing 5.75% of the Community area), based on rye and triticale crops, are estimated at 84,855, 74,906, 70,109, 50,791, 13,481, and 943 t annually for the Campiña, Vegas, Sur Occidental, Área Metropolitana, Lozoya-Somosierra, and Guadarrama regions. The latter represents a bioelectricity potential of 10.77, 9.5, 8.9, 6.44, 1.71, and 0.12 MW, respectively

Discovery of kilogauss magnetic fields in three DA white dwarfs

We have detected longitudinal magnetic fields between 2 and 4 kG in three (WD 0446$-$790, WD 1105$-$048, WD 2359$-$434) out of a sample of 12 normal DA white dwarfs by using optical spectropolarimetry done with the VLT Antu 8 m telescope equipped with FORS1. With the exception of 40 Eri B (4 kG) these are the first positive detections of magnetic fields in white dwarfs below 30 kG. Although suspected, it was not clear whether a significant fraction of white dwarfs contain magnetic fields at this level. These fields may be explained as fossil relics from magnetic fields in the main-sequence progenitors considerably enhanced by magnetic flux conservation during the shrinkage of the core. A detection rate of 25 % (3/12) may indicate now for the first time that a substantial fraction of white dwarfs have a weak magnetic field. This result, if confirmed by future observations, would form a cornerstone for our understanding on the evolution of stellar magnetic fields. Keywords: stars: white dwarfs - stars: magnetic fields - stars: individual: WD0446-790, WD1105-048, WD2359-434Comment: 15 pages, 7 figures, Astronomy and Astrophysics, in pres

The swastika as representation of the Sun of Helios and Mithras

At the 20th International Conference of the European Society for Astronomy in Cul- ture, held in Slovenia in 2012, Reza Assasi (2013) presented the paper ‘Swastika: The For- gotten Constellation Representing the Chariot of Mithras’, in which he identified Mithras and his quadriga with the constellation Draco, centre of the zodiac in the map of the stars. Thus he proposed a new interpretation that contradicted that accepted by researchers of the Mithraic religion who associate Mithras with the sun. This article aims to show that, contrary to this new interpretation, Mithras should still be identified with the solar deity. Mithraic iconography and liturgy is analysed in the present work, paying special attention to the relationship between the two solar deities Helios and Mithras. The context in which the swastika is depicted is analysed, demon- strating that it never represented a constellation but instead represented the sun. We fol- low the theory of David Ulansey (1994), which asserts that Mithras should be identified with the “hypercosmic sun”, the sphere of fire which Greek philosophers located beyond the starry heavens

Analyzing online search patterns of music festival tourists

Music festivals, as cultural events that induce tourism flows, intermediate both the cultural and travel experience. The present study analyzes online search behavior of potential attenders to a music festival. We hypothesize that the search process reveals latent patterns of behavior of cultural tourists planning to attend music festivals. To this end, information from Google Trends on queries related to three popular music festivals is used to build a network of search topics. Based on it, alternative exponential random graph model specifications are estimated. Findings support the general result of mediated information flows: music festivals induce planning and traveling queries. However, differences relating to the specificities of the cultural event are also found, in particular those regarding what nodes or queries supply the network with more useful information

Estudi de l'anoditzat d'alumini: A6061/AI203/26p T6, A359/SiC/20p T6 i A356 (New-Rheocasting)

En aquest projecte es pretén l’estudi de la capa d’anoditzat d’alumini amb tres materials bases diferents. A6061/Al2o3/26p T6 conformat per forja, A359/SiC/20p T6 conformat per fundició i A356 conformat en estat semi-sólid pel procés New Rehocasting. Per realitzar aquest estudi s’han efectuat un seguit d’assaigs per tal d’obtenir diferents propietats com ara la ultramicroduresa “Ultramicroduròmetre FISHERSCOPE H-100”,coeficient de fricció i velocitat de desgast “Tribòmetre Pin-on-Disc CSEM”, rugositat “TAYLOR-HOBSON Rugosimetre- Perfilómetre” i espessor de capa “Equip d’anàlisi d’imatges LEICA”. Posteriorment, s’ha realitzat l’anàlisi dels resultats i s’han extret les pertinents conclusions