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Sin resume

Propagation of Statistical and Nuclear Data Uncertainties in Monte-Carlo Burn-up Calculations

Two methodologies to propagate the uncertainties on the nuclide inventory in combined Monte Carlo-spectrum and burn-up calculations are presented, based on sensitivity/uncertainty and random sampling techniques (uncertainty Monte Carlo method). Both enable the assessment of the impact of uncertainties in the nuclear data as well as uncertainties due to the statistical nature of the Monte Carlo neutron transport calculation. The methodologies are implemented in our MCNP–ACAB system, which combines the neutron transport code MCNP-4C and the inventory code ACAB. A high burn-up benchmark problem is used to test the MCNP–ACAB performance in inventory predictions, with no uncertainties. A good agreement is found with the results of other participants. This benchmark problem is also used to assess the impact of nuclear data uncertainties and statistical flux errors in high burn-up applications. A detailed calculation is performed to evaluate the effect of cross-section uncertainties in the inventory prediction, taking into account the temporal evolution of the neutron flux level and spectrum. Very large uncertainties are found at the unusually high burn-up of this exercise (800 MWd/kgHM). To compare the impact of the statistical errors in the calculated flux with respect to the cross uncertainties, a simplified problem is considered, taking a constant neutron flux level and spectrum. It is shown that, provided that the flux statistical deviations in the Monte Carlo transport calculation do not exceed a given value, the effect of the flux errors in the calculated isotopic inventory are negligible (even at very high burn-up) compared to the effect of the large cross-section uncertainties available at present in the data files

Wind tunnel analysis of the aerodynamic loads on rolling stock over railway embankments: the effect of shelter windbreaks

Wind-flow pattern over embankments involves an overexposure of the rolling stock travelling on them to wind loads. Windbreaks are a common solution for changing the flow characteristic in order to decrease unwanted effects induced by the presence of crosswind. The shelter effectiveness of a set of windbreaks placed over a railway twin-track embankment is experimentally analysed. A set of two-dimensional wind tunnel tests are undertaken and results corresponding to pressure tap measurements over a section of a typical high-speed train are herein presented.The results indicate that even small-height windbreaks provide sheltering effects to the vehicles. Also, eaves located at the windbreak tips seem to improve their sheltering effect

Body-related attentional bias among men with high and low muscularity dissatisfaction

Previous studies have found gender differences in body-related attentional bias (AB), with women showing AB towards weight-related body parts. However, few studies have assessed the relationship between body-related AB and muscularity dissatisfaction (MD) in men. This study aimed to assess the presence of muscle-related AB in men, using a combination of a virtual reality (VR) embodiment-based technique and eye-tracking (ET) technology. Twenty men with high MD and 20 with low MD, owned a virtual avatar that had the same silhouette and body mass index as the participant. To analyze the gaze data, muscle-related areas of interest (M-AOIs) and nonmuscle-related areas of interest (NM-AOIs) were defined. The complete fixation time and the number of fixations on each AOI were recorded. Mixed between (group)-within (AOI_condition) analyses of variance showed a statistically significant interaction between group and time (p < 0.05) in both AB measures. Follow-up analyses revealed an AB towards M-AOIs only in men with high MD. Overall, men with high MD spent more time looking and displayed a higher number of fixations on M-AOIs, specifically the chest and shoulders, compared to men with low MD. This study provides new information about the relationship between MD and body-related AB in men. Combining VR with ET technologies presents interesting opportunities in the study of body image in men

Impact of different correlation structures in cross-section covariance matrices on the inventory and inventory-related parameters

At present, cross section correlation data are very poorly known. This work can be helpful to evaluate the effort that the international community should devote to the improvement of correlation data for inventory prediction in nuclear systems. Our purpose is to assess the impact of different correlation structures on the uncertainties in relevant fuel cycle and repository parameters, using fixed variances/diagonal values in the cross section covariance matrices. At this stage, only correlation in energy is taken into account, and no correlation among different types of nuclear reactions or different isotopes is considered. To accomplish this goal, the inventory code ACAB is used to estimate the uncertainties in the actinide concentrations of the irradiated fuel, related decay heat and dose (radiotoxicity) in a representative ADS irradiation scenario. It is shown that the nature of the introduced correlations is very relevant to estimate the overall uncertainty in those parameters, and then, the need of more scientifically based correlation data is clearly justified

Evaluation and improvement of empirical models of global solar irradiation: Case study northern Spain

This paper presents a new methodology to build parametric models to estimate global solar irradiation adjusted to specific on-site characteristics based on the evaluation of variable im- portance. Thus, those variables higly correlated to solar irradiation on a site are implemented in the model and therefore, different models might be proposed under different climates. This methodology is applied in a study case in La Rioja region (northern Spain). A new model is proposed and evaluated on stability and accuracy against a review of twenty-two already exist- ing parametric models based on temperatures and rainfall in seventeen meteorological stations in La Rioja. The methodology of model evaluation is based on bootstrapping, which leads to achieve a high level of confidence in model calibration and validation from short time series (in this case five years, from 2007 to 2011). The model proposed improves the estimates of the other twenty-two models with average mean absolute error (MAE) of 2.195 MJ/m2 day and average confidence interval width (95% C.I., n=100) of 0.261 MJ/m2 day. 41.65% of the daily residuals in the case of SIAR and 20.12% in that of SOS Rioja fall within the uncertainty tolerance of the pyranometers of the two networks (10% and 5%, respectively). Relative differences between measured and estimated irradiation on an annual cumulative basis are below 4.82%. Thus, the proposed model might be useful to estimate annual sums of global solar irradiation, reaching insignificant differences between measurements from pyranometers

Intensidad de Turbulencia en la Catenaria Inducida por Barreras Cortavientos en Viaductos.

El viento lateral puede comprometer tanto la operación segura de los trenes de alta velocidad, especialmente en tramos de vía desprotegidos, como la regularidad del servicio, ya que puede generar oscilaciones de gran amplitud en la catenaria por efectos de galope. La instalación de barreras cortaviento permite reducir las cargas aerodinámicas inducidas por el viento lateral sobre el tren, pero también influye en el nivel de intensidad de turbulencia en los cables de contacto de la catenaria. Para estimar la influencia del ángulo de ataque y de distintas barreras cortavientos, se han realizado una serie de ensayos en túnel aerodinámico para medir la intensidad de turbulencia en la catenaria. Mediante un equipo de anemometría de hilo caliente se obtienen las series temporales de velocidad de viento de una configuración bidimensional del problema, a partir de las cuales se determina la intensidad de turbulencia. Los ensayos muestran, como se podía esperar, que la intensidad de turbulencia en el hilo de contacto aumenta cuando la estela generada por el parapeto incide sobre la catenaria

Impact of different correlation structures in cross-section covariance matrices on the inventory and inventory-related parameters

Abstract At present, cross section correlation data are very poorly known. This work can be helpful to evaluate the effort that the international community should devote to the improvement of correlation data for inventory prediction in nuclear systems. Our purpose is to assess the impact of different correlation structures on the uncertainties in relevant fuel cycle and repository parameters, using fixed variances/diagonal values in the cross section covariance matrices. At this stage, only correlation in energy is taken into account, and no correlation among different types of nuclear reactions or different isotopes is considered. To accomplish this goal, the inventory code ACAB is used to estimate the uncertainties in the actinide concentrations of the irradiated fuel, related decay heat and dose (radiotoxicity) in a representative ADS irradiation scenario. It is shown that the nature of the introduced correlations is very relevant to estimate the overall uncertainty in those parameters, and then, the need of more scientifically based correlation data is clearly justified

Green determination of brominated flame retardants and organochloride pollutants in fish oils by vortex assisted liquid-liquid microextraction and gas chromatography-tandem mass spectrometry

A "green", simple, and low-cost sample extraction procedure involving the use of a deep eutectic solvent (DES) in a vortex assisted liquid-liquid microextraction (VALLME) technique followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis was developed for the simultaneous determination of different PBDEs congeners and OCPs residues in fish oils. After evaluation of different eutectic mixtures, the extraction parameters (volume of DES, amount of oil sample and extraction time) were optimized by means of experimental design in order to maximise extraction efficiency. The developed method was validated in terms of linearity, accuracy and precision, presenting limits of detection in the low ng g−1 level. Its application in the analysis of five fish oil samples, allowed the detection of all the target analytes at levels up 21.5 ng g−1. Fish oils used in animal feed showed to be more contaminated than fish oils for human consumption.Sara C. Cunha and José O. Fernandes thanks REQUIMTE, FCT Fundação para a Ciência e a Tecnologia) and FEDER through the project UID/ QUI/50006/2013 - POCI/01/0145/FEDER/007265 with financial support from FCT/MEC through national funds and co-financed by FEDER, under the Partnership Agreement PT2020. Sara C. Cunha acknowledges FCT for IF/01616/2015 contract. Angela G. Solaesa acknowledges University of Burgos for her pre-doctoral contract and Iberoamerican Santander Research Grant (2017) for the mobility financial support. Thanks to European Regional Development Fund (ERDF) and Junta de Castilla y León for financial support of project BU055U16