La Ingeniería Divertida: Gravity Challenge.

La competición se utiliza en muchos entornos educativos, especialmente en el ámbito anglosajón, como medio para contribuir al desarrollo de las habilidades de los alumnos, aspecto este que se encuentra íntimamente ligado a la adquisición de determinadas competencias profesionales. En el sector de la ingeniería y arquitectura resulta de gran importancia y por ello, la Universidad Politécnica de Madrid ha organizado durante el curso 2006‐07 un conjunto de competiciones de estudiantes muy diversas. Una de estas competiciones es la denominada GRAVITY CHALLENGE, en la que los equipos participantes se enfrentaban al reto de lanzar un huevo desde una altura de 15 metros y conseguir que aterrice en el suelo sin romperse. Los equipos ganadores serían aquellos que lograsen este objetivo de la forma más creativa. En este trabajo se describe el procedimiento seguido para la organización de esta competición en la que participaron 27 equipos de distintas universidades. También se presentan los resultados y se hace una reflexión sobre los objetivos formativos que consideramos alcanzados

Surface magnetism in ZnO/Co3O4 mixtures

We recently reported the observation of room temperature ferromagnetism in mixtures of ZnO and Co3O4 despite the diamagnetic and antiferromagnetic character of these oxides respectively. Here we present a detailed study on the electronic structure of this material in order to account for this unexpected ferromagnetism. Electrostatic interactions between both oxides lead to a dispersion of Co3O4 particles over the surface of ZnO larger ones. As a consequence, the reduction of Co+3 to Co2+ at the particle surface takes place as evidenced by XAS measurements and optical spectrocopy. This reduction allows to xplain the observed ferromagnetic signal within the well established theories of magnetism.Comment: Accepted in Journal of Applied Physic

Design and Implementation of a HardwareModule for MIMO Decoding in a 4G Wireless Receiver

Future 4th Generation (4G) wireless multiuser communication systems will have to provide advanced multimedia services to an increasing number of users, making good use of the scarce spectrum resources. Thus, 4G systemdesign should pursue both highertransmission bit rates and higher spectral efficiencies. To achieve this goal,multiple antenna systems are called to play a crucial role. In this contribution we address the implementation in FPGAs of a multiple-input multiple-output (MIMO) decoder embedded in a prototype of a 4G mobile receiver. This MIMO decoder is part of a multicarrier code-division multiple-access (MC-CDMA) radio system, equipped with multiple antennas at both ends of the link, that is able to handle up to 32 users and provides raw transmission bit-rates up to 125 Mbps. The task of the MIMO decoder is to appropriately combine the signals simultaneously received on all antennas to construct an improved signal, free of interference, from which to estimate the transmitted symbols. A comprehensive explanation of the complete design process is provided, including architectural decisions, floating-point to fixedpoint translation, and description of the validation procedure. We also report implementation results using FPGA devices of the Xilinx Virtex-4 family

Crystal structure of cobalt hydroxide carbonate Co2CO3(OH)(2): density functional theory and X-ray diffraction investigation

The cobalt carbonate hydroxide Co2CO3(OH)2 is a technologically important solid which is used as a precursor for the synthesis of cobalt oxides in a wide range of applications. It also has relevance as a potential immobilizer of the toxic element cobalt in the natural environment, but its detailed crystal structure is so far unknown. The structure of Co2CO3(OH)2 has now been investigated using density functional theory (DFT) simulations and powder X-ray diffraction (PXRD) measurements on samples synthesized via deposition from aqueous solution. Two possible monoclinic phases are considered, with closely related but symmetrically different crystal structures, based on those of the minerals malachite [Cu2CO3(OH)2] and rosasite [Cu1.5Zn0.5CO3(OH)2], as well as an orthorhombic phase that can be seen as a common parent structure for the two monoclinic phases, and a triclinic phase with the structure of the mineral kolwezite [Cu1.34Co0.66CO3(OH)2]. The DFT simulations predict that the rosasite-like and malachite-like phases are two different local minima of the potential energy landscape for Co2CO3(OH)2 and are practically degenerate in energy, while the orthorhombic and triclinic structures are unstable and experience barrierless transformations to the malachite phase upon relaxation. The best fit to the PXRD data is obtained using a rosasite model [monoclinic with space group P1121/n and cell parameters a = 3.1408 (4) Å, b = 12.2914 (17) Å, c = 9.3311 (16) Å and γ = 82.299 (16)°]. However, some features of the PXRD pattern are still not well accounted for by this refinement and the residual parameters are relatively poor. The relationship between the rosasite and malachite phases of Co2CO3(OH)2 is discussed and it is shown that they can be seen as polytypes. Based on the similar calculated stabilities of these two polytypes, it is speculated that some level of stacking disorder could account for the poor fit of the PXRD data. The possibility that Co2CO3(OH)2 could crystallize, under different growth conditions, as either rosasite or malachite, or even as a stacking-disordered phase intermediate between the two, requires further investigation

Short-Term Price Forecasting Models Based on Artificial Neural Networks for Intraday Sessions in the Iberian Electricity Market

This paper presents novel intraday session models for price forecasts (ISMPF models) for hourly price forecasting in the six intraday sessions of the Iberian electricity market (MIBEL) and the analysis of mean absolute percentage errors (MAPEs) obtained with suitable combinations of their input variables in order to find the best ISMPF models. Comparisons of errors from different ISMPF models identified the most important variables for forecasting purposes. Similar analyses were applied to determine the best daily session models for price forecasts (DSMPF models) for the day-ahead price forecasting in the daily session of the MIBEL, considering as input variables extensive hourly time series records of recent prices, power demands and power generations in the previous day, forecasts of demand, wind power generation and weather for the day-ahead, and chronological variables. ISMPF models include the input variables of DSMPF models as well as the daily session prices and prices of preceding intraday sessions. The best ISMPF models achieved lower MAPEs for most of the intraday sessions compared to the error of the best DSMPF model; furthermore, such DSMPF error was very close to the lowest limit error for the daily session. The best ISMPF models can be useful for MIBEL agents of the electricity intraday market and the electric energy industry

Application of the response surface method to optimize alkali activated cements based on low-reactivity ladle furnace slag

Steel-making slags, resulting from basic oxygen furnaces or electric arc furnaces are heavily applied in the construction industry, as an aggregate for pavements or concrete. Although possessing a significant crystalline content, it is expected that, if properly milled, the reactivity of these slags can increase up to a point when they are viable to produce alkaline cements. The aim of this study was the application of a response surface method to design the experimental work required to optimise the composition of an alkaline cement based on ladle furnace slag, a specific type of steel slag (SG). Fly ash (FA) was also added, in a precursor role, and the activation was achieved with an alkaline solution prepared with sodium silicate (SS) and sodium hydroxide (SH). The factors/variables considered were the activator index X = SS/(SS + SH), the precursor index Y = SG/(SG + FA) and the SH concentration (Z). The output variables were the unconfined compression strength and the flexural strength, after 7 and 28 days curing. Results indicate that the activator index (X) was the most influential variable, followed by the precursor index (Y). Microstructural analysis of selected pastes was also performed, using scanning electron microscopy and energy dispersive spectroscopy. The ideal composition obtained for the alkaline cement was the mixture constituted by X = 0.75, Y = 0.5 and Z = 10 (activator: 75% SS and 25% SH; precursor: 50% SG and 50% FA; SH concentration = 10 molal). This mixture achieved 8.70 MPa of flexural strength and 44.25 MPa of compressive strength which is reasonable for the required application (soil stabilisation)

Live Demonstration:Neuromorphic Sensory Integration for Combining Sound Source Localization and Collision Avoidance

The brain is able to solve complex tasks in real time by combining different sensory cues with previously acquired knowledge. Inspired by the brain, we designed a neuromorphic demonstrator which combines auditory and visual input to find an obstacle free direction closest to the sound source. The system consists of two event-based sensors (the eDVS for vision and the NAS for audition) mounted onto a pan-tilt unit and a spiking neural network implemented on the SpiNNaker platform. By combining the different sensory information, the demonstrator is able to point at a sound source direction while avoiding obstacles in real time