Broadband transverse susceptibility in multiferroic Y-type hexaferrite Ba0.5Sr1.5Zn2Fe12O22

Producción CientíficaNoncollinear spin systems with magnetically induced ferroelectricity from changes in spiral magnetic ordering have attracted significant interest in recent research due to their remarkable magnetoelectric effects with promising applications. Single phase multiferroics are of great interest for these new multifunctional devices, being Y-type hexaferrites good candidates, and among them the ZnY compounds due to their ordered magnetic behaviour over room temperature. Polycrystalline Y type hexaferrites with composition Ba0.5Sr1.5Zn2Fe2O22 (BSZFO) were sintered in 1050 °C–1250 °C temperature range. Transverse susceptibility measurements carried out on these BSZFO samples in the temperature range 80–350 K with DC fields up to ± 5000 Oe reveal different behaviour depending on the sintering temperature. Sample sintered at 1250 °C is qualitatively different, suggesting a mixed Y and Z phase like CoY hexaferrites. Sintering at lower temperatures produce single phase Y-type, but the transverse susceptibility behaviour of the sample sintered at 1150 °C is shifted at temperatures 15 K higher. Regarding the DC field sweeps the observed behaviour is a peak that shifts to lower values with increasing temperature, and the samples corresponding to single Y phase exhibit several maxima and minima in the 250 K–330 K range at low DC applied field as a result of the magnetic field induced spin transitions in this compound.Ministerio de Ciencia, Innovación y Universidades; Agencia Estatal de Investigación with FEDER (MAT2016-80784-P

Pedestrian Detection in Crowded Environments through Bayesian Prediction of Sequential Probability Matrices

In order to safely navigate populated environments, an autonomous vehicle must be able to detect human shapes using its sensory systems, so that it can properly avoid a collision. In this paper, we introduce a Bayesian approach to the Viola-Jones algorithm, as a method to automatically detect pedestrians in image sequences. We present a probabilistic interpretation of the basic execution of the original tool and develop a technique to produce approximate convolutions of probability matrices with multiple local maxima

Detection of Musical Notes Using a Polyphonic Pitch Tracking Embedded System

Detection of polyphonic notes using embedded systems is a field that has not been explored. This article describes a polyphonic tracking embedded system that can detect on real time single and multiple musical notes, as well as their time duration. The solution was designed on an embedded system with a Cortex M-7 core as processor. This was achieved with an algorithm using fast Fourier transform iterating on two buffers in coordination with the direct memory access peripheral. The proposed embedded system was able to detect multiple musical notes on real time. Future works could use the results of this design and export them to a real music editing format.ITESO, A. C

Examination of the Feynman-Hibbs Approach in the Study of NeN_N-Coronene Clusters at Low Temperatures

Feynman-Hibbs (FH) effective potentials constitute an appealing approach for investigations of many-body systems at thermal equilibrium since they allow us to easily include quantum corrections within standard classical simulations. In this work we apply the FH formulation to the study of Ne$_N$-coronene clusters ($N=$ 1-4, 14) in the 2-14 K temperature range. Quadratic (FH2) and quartic (FH4) contributions to the effective potentials are built upon Ne-Ne and Ne-coronene analytical potentials. In particular, a new corrected expression for the FH4 effective potential is reported. FH2 and FH4 cluster energies and structures -obtained from energy optimization through a basin-hoping algorithm as well as classical Monte Carlo simulations- are reported and compared with reference path integral Monte Carlo calculations. For temperatures $T> 4$ K, both FH2 and FH4 potentials are able to correct the purely classical calculations in a consistent way. However, the FH approach fails at lower temperatures, especially the quartic correction. It is thus crucial to assess the range of applicability of this formulation and, in particular, to apply the FH4 potentials with great caution. A simple model of $N$ isotropic harmonic oscillators allows us to propose a means of estimating the cut-off temperature for the validity of the method, which is found to increase with the number of atoms adsorbed on the coronene molecule

Training Deep Gaussian Processes using Stochastic Expectation Propagation and Probabilistic Backpropagation

Deep Gaussian processes (DGPs) are multi-layer hierarchical generalisations of Gaussian processes (GPs) and are formally equivalent to neural networks with multiple, infinitely wide hidden layers. DGPs are probabilistic and non-parametric and as such are arguably more flexible, have a greater capacity to generalise, and provide better calibrated uncertainty estimates than alternative deep models. The focus of this paper is scalable approximate Bayesian learning of these networks. The paper develops a novel and efficient extension of probabilistic backpropagation, a state-of-the-art method for training Bayesian neural networks, that can be used to train DGPs. The new method leverages a recently proposed method for scaling Expectation Propagation, called stochastic Expectation Propagation. The method is able to automatically discover useful input warping, expansion or compression, and it is therefore is a flexible form of Bayesian kernel design. We demonstrate the success of the new method for supervised learning on several real-world datasets, showing that it typically outperforms GP regression and is never much worse

Innermost stable circular orbits around magnetized rotating massive stars

In 1998, Shibata and Sasaki [Phys. Rev. D 58, 104011 (1998)] presented an approximate analytical formula for the radius of the innermost stable circular orbit (ISCO) of a neutral test particle around a massive, rotating and deformed source. In the present paper, we generalize their expression by including the magnetic dipole moment. We show that our approximate analytical formulas are accurate enough by comparing them with the six-parametric exact solution calculated by Pach\'on et. al. [Phys. Rev. D 73, 104038 (2006)] along with the numerical data presented by Berti and Stergioulas [MNRAS 350, 1416 (2004)] for realistic neutron stars. As a main result, we find that in general, the radius at ISCO exhibits a decreasing behavior with increasing magnetic field. However, for magnetic fields below 100GT the variation of the radius at ISCO is negligible and hence the non-magnetized approximate expression can be used. In addition, we derive approximate analytical formulas for angular velocity, energy and angular momentum of the test particle at ISCO.Comment: 8 pages, 3 figure

From a FPGA Prototyping Platform to a Computing Platform: The MANGO Experience

[EN] In this paper we describe the evolution of the FPGA-based prototype deployed in the MANGO project, from a hardware prototyping platform of HPC architectures to a computing platform targeting HPC and AI applications. Our main goal is to reinvest on the MANGO cluster by providing a duality in its use for both large-scale hardware prototyping and highperformance computation. From our experience we can reach several interesting conclusions about the complexities and hurdles that lay below FPGA technologies, and therefore, shedding some light onto the real complexities that difficult the adoption of FPGAs on either large-scale pure HPC systems or on hybrid systems (HPC + BigData/Ai).This work is supported by the European Commission through RECIPE and DeepHealth projects, under the Horizon 2020 program, grant number 801137 and 825111, respectively.Flich Cardo, J.; Tornero-Gavilá, R.; Rodríguez, D.; Russo, D.; Martínez Martínez, JM.; Hernández Luz, C. (2021). From a FPGA Prototyping Platform to a Computing Platform: The MANGO Experience. IEEE. 1-6. https://doi.org/10.23919/DATE51398.2021.94740511

Ceramic dies selection for electrical resistance sintering of metallic materials

Processing metallic powders by electrical resistance sintering requires the use of insulating ceramics dies. Selecting the appropriate ceramic material according to the electrical, thermal and mechanical properties is a need. Dies produced with several ceramic materials have been tested during the production of cemented carbide in order to check their behaviour in the process and final product properties. Tialite/mullite, zircon/mullite, zirconium phosphate based ceramic, yttria-stabilized zirconia and sialon, in most cases with modified compositions and shaping processes in order to achieve a high density, have been tested. Dry powder processing by cold isostatic pressing and furnace sintering resulted to be the better process for dies production. The effect of die properties on the produced cemented carbide, and the behaviour and life of the die during the production have been analysed. Very smooth die surface increases the number of cycles withstood during metallic parts production, because of lower extraction stresses, as checked for sialon dies. Zirconium phosphate based dies, with low thermal conductivity, show the most densified hard metal parts surface.Pproject EFFIPRO (EU) FP7-2013-NMP-ICT-FoF GRANT AGREEMENT N° 6087

Evaluation of the effect of different insecticides on the survival and capacity of 2 Eretmocerus mundus Mercet to control Bemisia tabaci (Gennadius) populations

Two different experiments were carried out to evaluate three insecticides. In the 24 first one, the effect of two insecticides, methomyl and indoxacarb, on pupae and 25 adults of the whitefly Bemisia tabaci (Gennadius) parasitoid Eretmocerus mundus 26 Mercet was evaluated under laboratory and greenhouse conditions, using sweet 27 pepper (Capsicum annuum L.) plants. In the second experiment, oxamyl was 28 tested to study its effect on the ability of E. mundus to parasitize and control B. 29 tabaci in sweet pepper plants, using a greenhouse cage evaluation. Methomyl and 30 indoxacarb caused low mortality of E. mundus pupae (17.6 and 7.8% 31 respectively), although methomyl mortality was significantly higher. Methomyl 32 produced 100% mortality on E. mundus adults with fresh and 24 hour-old 33 residues on leaves, significantly higher than the mortality produced by indoxacarb 34 (values ranged from 43.9 to 34.4%). The harmful effect of methomyl persisted for 35 a long time (up to 60 days). The results of the experiment with oxamyl showed 36 that E. mundus controlled whitefly population, without significant interaction 37 between the presence of the parasitoid and insecticide on whitefly mortality. 38 Whitefly mortality in the presence of the parasitoid was 87.8%, significantly higher 39 than the mortality in the absence of E. mundus (59.3%). Oxamyl did not produce 40 a significant effect on the emergence of E. mundus adults. Application of the 41 products in IPM programs is discussed