331 research outputs found
Iron-based reversible adhesives: Effect of particles size on mechanical properties
No full text A hot melt adhesive – mainly used for bonding plastic component in automotive field – was modified with different iron-based particles to give it a reversible behaviour. Mechanical and physical properties of these reversible adhesives were experimentally assessed in the work. The modified adhesives, coupled with electromagnetic induction, are able to guarantee separation of the joints without any damage to the substrates for recycling, reuse or repairing of components. Single lap joint specimens were prepared using epoxy/glass fibres substrates and tests were carried out on neat and modified adhesive with 5% weight of iron and iron oxide. Three different Fe particles size were tested: 450 µm, 60 µm and 1–6 µm. The particles size of iron oxide was 50 nm. Separation was studied using single lap joint specimens under electro-magnetic induction. Experimental results showed that the maximum peak load decreases when the average particles sizes increase. The peak loads of the smallest particles were equal to the ones of the pristine adhesive. The elongation of the adhesives increases when the adhesive is modified with both iron and iron oxide particles. Finally, experimental tests on single lap joints coupled with electro-magnetic induction showed that separation of the substrates is possible using iron oxide particles. Electro-magnetic tests conducted on particles alone, helped to understand that bigger particles are able to overcome the melting temperature of the adhesive but hot-melt adhesives modified with these particles are not able to reach the melting. These tests showed that the number of particles into the adhesive matrix is very important for this kind of tests. </jats:p
The Visegrad Group and the European Union’s ‘Eastern’ Dimension
No full textThe 2004 enlargement of the European Union (EU) changed the dynamics of its engagement with the former Soviet Republics which now constitute the Eastern neighbourhood. As well as manifold implications of the eastward shift of the EU
border and ‘acquisition of a shared neighbourhood with Russia, the enlarged EU now incorporated new member states with foreign policy concerns focused mostly on the Eastern neighbours. Four of the new member states – the Czech
Republic, Hungary, Poland and Slovakia – brought into the EU with them their own subregional alliance in the form of the Visegrad Group (VG). Since 2004 the ‘Visegrad 4’ (V4) have been attempting to develop an effective multilateral
contribution to EU ‘Eastern Policy’ and to reform processes in the WNIS. This paper argues that while there has been some evidence of an effective VG multilateral approach, in both inputs to EU Eastern policy and modest support
for broader ‘Europeanisation’ processes in WNIS, so far the VG has failed to achieve a lead role in EU Eastern policy and that a range of obstacles have limited the multilateral approach of the V4 in general
A novel electroluminescent PPV copolymer and silsesquioxane nanocomposite film for the preparation of efficient PLED devices
No full textA Varied History of an Influential Author/Publisher Society – The VG WORT
No full textDie Verwertungsgesellschaft Wort (VG WORT) beging 2008 ihr 50-jähriges Jubiläum. Zu diesem Anlass erschien der vorliegende Jubiläumsband von Thomas Keiderling. Auf anschauliche Weise führt er in das komplexe und zunächst unübersichtliche Aufgabengebiet der Verwertungsgesellschaft ein. Bei der VG WORT handelt es sich um eine privatrechtliche Interessenvertretung der Autoren und Verlage auf dem Gebiet des Urheberrechts. Ihre Vor- und Vereinsgeschichte wird kenntnisreich und problemorientiert dargestellt. Initiatoren und Gestalter dieser Vereinigung erhalten ein Gesicht, juristische Auseinandersetzungen und Musterprozesse werden detailliert besprochen. Sieben Essays von Wegbereitern und Protagonisten der Verwertungsgesellschaft runden die Darstellung ab. Die Arbeit stellt eine gut lesbare, für Fachinteressierten wie für Laien geeignete Geschichtsdarstellung der VG WORT dar.The Verwertungsgesellschaft Wort’s (VG WORT) fiftieth anniversary in 2008 occasioned this jubilee edition edited by Thomas Keiderling, whose task it is to introduce the complex and initially confusing remit of the Verwertungsgesellschaft (collecting society) in an accessible way: a non-profit collecting society that works on behalf of authors and publishers in matters of copyright. The society’s history and background are presented in a well-grounded and problem-oriented way. The book details the society’s founding, profiles prominent members and explicitly discusses law suits and test cases. Completing the volume are seven essays from some of the society’s leading innovators. Keiderling’s is a highly readable account of the VG WORT, suitable for scholars and laymen alike
Model Dependency of the Digital Option Replication – Replication under an Incomplete Model (in English)
No full textThe paper focuses on the replication of digital options under an incomplete model. Digital options are regularly applied in the hedging and static decomposition of many path-dependent options. The author examines the performance of static and dynamic replication. He considers the case of a market agent for whom the right model of the underlying asset-price evolution is not available. The observed price dynamic is supposed to follow four distinct models: (i) the Black and Scholes model, (ii) the Black and Scholes model with stochastic volatility driven by Hull and White model, (iii) the variance gamma model, defined as time changed Brownian motion, and (iv) the variance gamma model set in a stochastic environment modelled as the rate of time change via a Cox-Ingersoll-Ross model. Both static and dynamic replication methods are applied and examined within each of these settings. The author verifies the independence of the static replication on underlying processes.digital options, dynamic and static replication, internal time, Lévy models, replication error, stochastic environment, stochastic volatility, variance gamma process
Multiple piscine vitellogenins : biomarkers of fish exposure to estrogenic endocrine disruptors in aquatic environments
No full textVitellogenin (Vg), a major estrogen-inducible yolk precursor protein, has become an important biomarker for assessing the estrogenic potency of chemicals and the exposure of animals to estrogenic contaminants present in aquatic environments. These contaminants, which can disrupt functioning of the vertebrate neuroendocrine system, are known as endocrine disrupting chemicals (EDCs). In general, investigations of the significance of estrogenic EDCs have failed to keep pace with recent developments in our understanding of vitellogenesis in fishes. Recent gene cloning and immunobiochemical analyses have verified the general multiplicity of piscine Vg and led to exploration of the unique roles of yolk proteins derived from different forms of Vg in the processes of oogenesis and embryogenesis. The levels of circulating Vg proteins (or Vg gene transcripts) during oogenesis and their degree of induction by estrogens appear to vary among species and among different types of Vg within species. The kinetics of induction of distinct types of Vg by estrogens in fishes appears to depend on environmental factors (e.g., water temperature and photoperiod), life history stage, and the concentration and type of estrogenic compound. Consideration of these findings will contribute to development of Vg-based bioassays superior to those currently based on the outdated "single Vg" model
Genotype effect on lifespan following vitellogenin knockdown
No full textabstract: Honey bee workers display remarkable flexibility in the aging process. This plasticity is closely tied to behavioral maturation. Workers who initiate foraging behavior at earlier ages have shorter lifespans, and much of the variation in total lifespan can be explained by differences in pre-foraging lifespan. Vitellogenin (Vg), a yolk precursor protein, influences worker lifespan both as a regulator of behavioral maturation and through anti-oxidant and immune functions. Experimental reduction of Vg mRNA, and thus Vg protein levels, in wild-type bees results in precocious foraging behavior, decreased lifespan, and increased susceptibility to oxidative damage. We sought to separate the effects of Vg on lifespan due to behavioral maturation from those due to immune and antioxidant function using two selected strains of honey bees that differ in their phenotypic responsiveness to Vg gene knockdown. Surprisingly, we found that lifespans lengthen in the strain described as behaviorally and hormonally insensitive to Vg reduction. We then performed targeted gene expression analyses on genes hypothesized to mediate aging and lifespan: the insulin-like peptides (Ilp1 and 2) and manganese superoxide dismutase (mnSOD). The two honey bee Ilps are the most upstream components in the insulin-signaling pathway, which influences lifespan in Drosophila melanogaster and other organisms, while manganese superoxide dismutase encodes an enzyme with antioxidant functions in animals. We found expression differences in the llps in fat body related to behavior (llp1 and 2) and genetic background (Ilp2), but did not find strain by treatment effects. Expression of mnSOD was also affected by behavior and genetic background. Additionally, we observed a differential response to Vg knockdown in fat body expression of mnSOD, suggesting that antioxidant pathways may partially explain the strain-specific lifespan responses to Vg knockdown.NOTICE: this is the author's version of a work that was accepted for publication in EXPERIMENTAL GERONTOLOGY. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in EXPERIMENTAL GERONTOLOGY, 61, 113-122. DOI: 10.1016/j.exger.2014.12.00
Implementation and Analysis of a Semi-Empirical Vortex Generator Model in OpenFOAM
No full textPassive vortex generators (VGs) are small plate-devices that are placed on the top of wings, in an array configuration, in order to delay or event prevent stall. Due to their small size, when compared to the wing, a highly refined mesh is required to accurately simulate the flow behaviour downstream the VG location. As a consequence, the computational time required for a high fidelity 3D computational simulations is very large. In recent years, there have been efforts to create models that allow the computation of the VGs effect without grid them. Reducing this way the computational effort. During this thesis a semi-empirical model, the Wendt model, was implemented in OpenFOAM and later analysed and compared with gridded VG simulations. The Wendt model is used to predict the vortex circulation and peak vorticity. These entities are then used to calculate the vortex velocity profile at a certain position downstream the VG location. In this projects besides the predictive capabilities of the model, it was tested the hypothesis that to mimic the flow behaviour of a gridded VG simulation, it is enough to impose a vortex velocity profile at a certain position downstream the VG location. It was seen that the Wendt model is able to predict reasonably well peak vorticity and circulation on the tested parameter range, but for higher values of freestream velocities and lower values of height-to-boundary-layer-thickness-ratio and aspect ratio. Furthermore it was seen that, although the implemented model produce inconsistent flow results, the implementation made can be used for that propose. With the correct vortex circulation, peak vorticity and vortex position inputs, it is possible to mimic the correct vortex development as well as the correct flow behaviour, but only far from the VG location, where the influence of the vanes in the streamwise velocity is no longer relevant.Aerospace EngineeringAerodynamics, Wind Energy & PropulsionAerodynamic
Towards a Multi-Fidelity Approach for CFD Simulations of Vortex Generator Arrays
No full textThis paper is the starting point for the development of a multi-fidelity modeling approach for vortex generators (VG) arrays, where a fully resolved VG model will be coupled with an approximate model in order to improve both accuracy and flexibility without increasing the required computational cost. As a first step thereto, an analysis of the ability of the BAY-model to simulate incompressible flows around a VG on a flat plate has been performed. Results are presented for several turbulence models and using different cell selection approaches, where comparison is made with fully resolved VG results. In addition to a coarse uniform mesh, the BAY-model has been evaluated on a densely gridded mesh in order to distinguish between model and mesh related discrepancies.Aerodynamics, Wind Energy & PropulsionAerospace Engineerin
Comparison of volume guarantee and volume-controlled ventilation both using closed loop inspired oxygen in preterm infants: A randomised crossover study (CLIO-VG study)
No full text\ua9 Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.Objective: The objective of this study was to compare two different modes of ventilation in maintaining oxygen saturation (SpO2) in target range (90%-95%) in ventilated preterm infants cared for with automatic control of oxygen delivery (A-FiO2). Design: A single-centre randomised crossover study. Settings: A level III neonatal intensive care unit. Patients: Preterm infants receiving mechanical ventilation and oxygen requirement >21%. Interventions: Volume guarantee (VG) vs volume controlled ventilation (VCV) modes with automatic oxygen control (A-FiO2). Outcomes: The primary outcome of this study was the proportion of time spent with oxygen saturations in the target range (90%-95%). Results: Nineteen preterm infants with a median gestation age 25 weeks (IQR: 24-28) and birth weight 685 g (IQR: 595-980) were enrolled in the study. There was no significant difference in primary outcome of median proportion of time spent in target saturation between the two arms (72% (57-81) in VG vs 75% (58-83) in VCV; p=0.98). There was no significant difference in the secondary outcomes of time spent in SpO2 <80% (0.03% vs 0.14%; p=0.51), time spent in SpO2 >98% (0.50% vs 0.08%; p=0.54), the median FiO2 (31% vs 29%; p=0.51) or manual adjustments carried out between VG and VCV, respectively. The number of episodes of prolonged hypoxaemia and hyperoxaemia were similar in the two groups. Conclusion: There was no significant difference in time spent in target SpO2 range between VG and VCV when A-FiO2 was used as the FiO2 controller in this crossover randomised control study. Trial registration number: NCT03865069
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