Qualification of Fiber Reinforced Polymer materials (FRP’s) for manufacturing of structural components in the aerospace industry is usually associated with extensive and costly experimental ...campaigns. The burden of testing is immense and materials should be characterized under different loading states (tension, compression, shear) and environmental conditions (temperature, humidity) to probe their structural integrity during service life. Recent developments in multiscale simulation, together with increased computational power and improvements in modeling tools, can be used to alleviate this scenario. In this work, high-fidelity simulations of the material behavior at the micro level are used to predict ply properties and ascertain the effect of ply constituents and microstructure on the homogenized ply behavior. This approach relies on the numerical analysis of representative volume elements equipped with physical models of the ply constituents. Its main feature is the ability to provide fast predictions of ply stiffness and strength properties for different environmental conditions of temperature and humidity, in agreement with the experimental results, showing the potential to reduce the time and costs required for material screening and characterization.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We propose a novel approach to the study of compound extremes, grounded in dynamical systems theory. Specifically, we present the co‐recurrence ratio (α), which elucidates the dependence structure ...between variables by quantifying their joint recurrences. This approach is applied to daily climate extremes, derived from the ERA‐Interim reanalysis over the 1979–2018 period. The analysis focuses on concurrent (i.e., same‐day) wet (total precipitation) and windy (10 m wind gusts) extremes in Europe and concurrent cold (2 m temperature) extremes in Eastern North America and wet extremes in Europe. Results for wet and windy extremes in Europe, which we use as a test‐bed for our methodology, show that α peaks during boreal winter. High α values correspond to wet and windy extremes in northwestern Europe, and to large‐scale conditions resembling the positive phase of the North Atlantic Oscillation (NAO). This confirms earlier findings which link the positive NAO to a heightened frequency of extratropical cyclones impacting northwestern Europe. For the Eastern North America–Europe case, α extremes once again reflect concurrent climate extremes – in this case cold extremes over North America and wet extremes over Europe. Our analysis provides detailed spatial information on regional hotspots for these compound extreme occurrences, and encapsulates information on their spatial footprint which is typically not included in a conventional co‐occurrence analysis. We conclude that α successfully characterises compound extremes by reflecting the evolution of the associated meteorological maps. This approach is entirely general, and may be applied to different types of compound extremes and geographical regions.
Episodes of concurrent precipitation and wind extremes in Europe, and cold extremes in Eastern North America and precipitation extremes in Europe, can be diagnosed in terms of the coupling of the relevant climate variables. This is computed here using dynamical systems theory. Concurrent extremes generally occur when the large‐scale fields are strongly coupled. In Europe, for example, highly coupled states of precipitation and wind fields correspond to positive anomalies over the western/northern part of the continent (see figure), projecting onto the positive phase of the NAO.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The determination of ply properties of Fiber Reinforced Polymers (FRP) for particular operational environmental conditions in aeronautical applications is mandatory in order to fulfill current ...industry stringent certification requirements. However, the traditional experimental approach requires massive investments of resources and time. From the behaviour obtained experimentally, constitutive equations including failure criteria are then devised to be used in the design of FRP structures. The ply longitudinal behaviour under compression is generally the most difficult to measure and characterize. In this work, an alternative coupled experimental-computational micromechanics approach is proposed to determine the longitudinal compression properties of unidirectional FRP plies under different environmental conditions. This methodology includes experimental characterization of matrix and fiber/matrix interface, combined with numerical simulations of realistic microstructures. The interface decohesion is simulated using cohesive-frictional interactions. A pressure dependent, elasto-plastic model that includes tensile damage is employed to capture the matrix nonlinear behaviour. The numerical predictions match the experimentally-obtained ply properties available in the literature in a remarkable way and suggest that virtual ply property characterization is a mature and reliable approach to conduct screening of materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
► We investigate gender differences in anxiety and emotion dysregulation in youths. ► Girls report higher levels of anxiety and emotion dysregulation than boys. ► Emotion dysregulation significantly ...predicts anxiety in girls and boys. ► Emotion dysregulation better predictor of anxiety in girls than in boys. ► Different aspects of emotion dysregulation account for anxiety in boys and girls.
An increasing number of studies has shown that emotion dysregulation plays a key role in relation to childhood anxiety. While gender differences are commonly associated with emotional competence, no study has yet examined whether the relation between emotion dysregulation and anxiety is the same for girls as it is for boys. The present study investigated the possibility of gender differences in the relation between emotion dysregulation and anxiety in a community sample of 544 children and adolescents (298 girls and 246 boys) in the age of 9–16years. Anxiety was assessed using the Screen for Child Anxiety Related Emotional Disorders-Revised (SCARED-R). Emotion dysregulation was measured by the Difficulties in Emotion Regulation Scale (DERS). Four results emerged from this study. In accordance with previous research, (1) girls experience more anxiety and greater difficulties regulating their negative emotions than boys, and (2) emotion dysregulation has a significant impact on anxiety. Not previously shown, (3) emotion dysregulation is more predictive of anxiety in girls than in boys, and (4) different types of emotion regulation difficulties account for anxiety in girls and boys. Participants’ age did not have an impact on anxiety scores. Findings are discussed with respect to clinical implications and future directions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A fast I/Q imbalance compensation algorithm is presented. It is demonstrated through MATLAB simulations that with a few samples an image-to-signal ratio (ISR) lower than −25 dB was achieved. On the ...basis of digital processing of the received signal, this algorithm is compliant with low-cost and low-complexity wireless receivers because it does not require extra time and resources for calibration. Moreover, its fast convergence allows reaching a high enough image rejection ratio by adapting the compensation weight during the reception of a known preamble such as defined by the IEEE 802.15.4 or the Bluetooth low energy standards.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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