1,263 research outputs found

    Development of a real-time algorithm for detection of the divertor detachment radiation front using multi-spectral imaging

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    In this paper we present a novel algorithm to extract the optical plasma boundary and radiation front for detached divertor plasmas. We show that reliable detection of the divertor leg and radiation front is possible using lightweight image processing tools. Using a non-tomographic approach, the detected divertor leg and radiation front can be mapped to the poloidal plane. This approach is fast and accurate enough for real-time control purposes, allowing in particular real-time plasma shape and detachment control, and post-shot detachment physics and dynamics analysis.</p

    Haptic Shared Control in Tele-Manipulation: Effects of Inaccuracies in Guidance on Task Execution

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    Haptic shared control is a promising approach to improve tele-manipulated task execution, by making safe and effective control actions tangible through guidance forces. In current research, these guidance forces are most often generated based on pre-generated, errorless models of the remote environment. Hence such guidance forces are exempt from the inaccuracies that can be expected in practical implementations. The goal of this research is to quantify the extent to which task execution is degraded by inaccuracies in the model on which haptic guidance forces are based. In a human-in-the-loop experiment, subjects (n = 14) performed a realistic tele-manipulated assembly task in a virtual environment. Operators were provided with various levels of haptic guidance, namely no haptic guidance (conventional tele-manipulation), haptic guidance without inaccuracies, and haptic guidance with translational inaccuracies (one large inaccuracy, in the order of magnitude of the task, and a second smaller inaccuracy). The quality of natural haptic feedback (i.e., haptic transparency) was varied between high and low to identify the operator\u27s ability to detect and cope with inaccuracies in haptic guidance. The results indicate that haptic guidance is beneficial for task execution when no inaccuracies are present in the guidance. When inaccuracies are present, this may degrade task execution, depending on the magnitude and the direction of the inaccuracy. The effect of inaccuracies on overall task performance is dominated by effects found for the Constrained Translational Movement, due to its potential for jamming. No evidence was found that a higher quality of haptic transparency helps operators to detect and cope with inaccuracies in the haptic guidance.</p

    The degree of joint range of motion limitations after burn injuries during recovery

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    Introduction: The aim of this study was to determine the degree of ROM limitations of extremities, joints and planes of motion after burns and its prevalence over time. Method: The database of a longitudinal multicenter cohort study in the Netherlands (2011–2012) was used. From patients with acute burns involving the neck, shoulder, elbow, wrist, hip, knee and ankle joints that had surgery, ROM of 17 planes of motion was assessed by goniometry at 3, 6 weeks, 3–6–9 and 12 months after burns and at discharge. Results: At 12 months after injury, 12 out of 17 planes of motion demonstrated persistent joint limitations. The five unlimited planes of motion were all of the lower extremity. The most severely limited joints at 12 months were the neck, ankle, wrist and shoulder. The lower extremity was more severely limited in the early phase of recovery whereas at 12 months the upper extremity was more severely limited. Conclusion: The degree of ROM limitations and prevalence varied over time between extremities, joints and planes of motion. This study showed which joints and planes of motion should be watched specifically concerning the development of scar contracture

    Sediment Transport of Fine Sand to Fine Gravel on Transverse Bed Slopes in Rotating Annular Flume Experiments

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    Large‐scale morphology, in particular meander bend depth, bar dimensions, and bifurcation dynamics, are greatly affected by the deflection of sediment transport on transverse bed slopes due to gravity and by secondary flows. Overestimating the transverse bed slope effect in morphodynamic models leads to flattening of the morphology, while underestimating leads to unrealistically steep bars and banks and a higher braiding index downstream. However, existing transverse bed slope predictors are based on a small set of experiments with a minor range of flow conditions and sediment sizes, and in practice models are calibrated on measured morphology. The objective of this research is to experimentally quantify the transverse bed slope effect for a large range of near‐bed flow conditions with varying secondary flow intensity, sediment sizes (0.17–4 mm), sediment transport mode, and bed state to test existing predictors. We conducted over 200 experiments in a rotating annular flume with counterrotating floor, which allows control of the secondary flow intensity separate from the streamwise flow velocity. Flow velocity vectors were determined with a calibrated analytical model accounting for rough bed conditions. We isolated separate effects of all important parameters on the transverse slope. Resulting equilibrium transverse slopes show a clear trend with varying sediment mobilities and secondary flow intensities that deviate from known predictors depending on Shields number, and strongly depend on bed state and sediment transport mode. Fitted functions are provided for application in morphodynamic modelin

    Mercury in the Black Sea:New Insights From Measurements and Numerical Modeling

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    Redox conditions and organic matter control marine methylmercury (MeHg) production. The Black Sea is the world's largest and deepest anoxic basin and is thus ideal to study Hg species along the extended redox gradient. Here we present new dissolved Hg and MeHg data from the 2013 GEOTRACES MEDBlack cruise (GN04_leg2) that we integrated into a numerical 1-D model, to track the fate and dynamics of Hg and MeHg. Contrary to a previous study, our new data show highest MeHg concentrations in the permanently anoxic waters. Observed MeHg/Hg percentage (range 9-57%) in the anoxic waters is comparable to other subsurface maxima in oxic open-ocean waters. With the modeling we tested for various Hg methylation and demethylation scenarios along the redox gradient. The results show that Hg methylation must occur in the anoxic waters. The model was then used to simulate the time evolution (1850-2050) of Hg species in the Black Sea. Our findings quantify (1) inputs and outputs of Hg-T (similar to 31 and similar to 28 kmol yr(-1)) and MeHgT (similar to 5 and similar to 4 kmol yr(-1)) to the basin, (2) the extent of net demethylation occurring in oxic (similar to 1 kmol yr(-1)) and suboxic water (similar to 6 kmol yr(-1)), (3) and the net Hg methylation in the anoxic waters of the Black Sea (similar to 11 kmol yr(-1)). The model was also used to estimate the amount of anthropogenic Hg (85-93%) in the Black Sea

    roma westward migration in europe rethinking political social and methodological challenges

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    The idea for this book stemmed from two symposia that brought together scholars from a range of different countries and disciplines to reflect upon the political and legal context of the mobility of Romani citizens in Europe. Our interest in this topic started with the adoption of a EU Framework for National Roma Integration Strategies in 2011, when Member States were requested to develop integration strategies that were explicitly yet not exclusively targeted at their Roma populations (European Commission 2011). Even though this policy scheme represented an effort to overcome the inadequacies of the anti-discrimination directives to address the social and institutional discrimination suffered by Roma people in Europe, tangible results of such measures have so far been lacking. The symposia, titled "Roma Westward Migration in Europe: Rethinking Political, Social, and Methodological Challenges", addressed the emergence of Roma-specific policies alongside an increasing concern about migration and diversity management. The drive to bring together different disciplinary and methodological approaches to "Roma migration" in Europe, and to explore how such phenomenon has been narrated, policed, politicized or ignored was – and is – rooted in four main considerations. Firstly, we are convinced that putting the focus squarely on the so-called "Roma westward migration" and problematizing the assumptions that underpin such a label contributes to uncover the structural inconsistencies of the European "Roma integration" framework and to question its overall political approach. Secondly, the intersections and overlaps between the categories of "Roma" and of "migrants" show how the classifications of deservingness and of access to welfare resources have shifted in recent years, making explicit the under-studied link between inclusive and securitarian policies. Thirdly, we believe that "Roma migration" provides a unique testing ground to understand how those portrayed as "the others" in contemporary Europe cope and develop counter-strategies in a system in which their options are limited. Fourthly and finally, we strongly support ethnographic accounts as a useful means to evaluate public policies at the local level, as they offer rich data that cannot be captured by national statistics or by surveys alone
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