1,632 research outputs found

    Nonlinear dynamics aspects of subcritical transitions and singular flows in viscoelastic fluids

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    Recently, there has been a renewed interest in theoretical aspects of flows of viscoelastic fluids (such as dilute polymer solutions). This thesis addresses two distinct issues related to such flows. Motivated by the possible occurrence of subcritical (finite-amplitude) instabilities in parallel flows - instabilities that cannot be captured by the usual linear stability analyses - I present and evaluate a method to describe these subcritical transitions by means of a direct expansion in the amplitude of the linearly least stable mode. A second issue is the behaviour of viscoelastic fluids in steady elongational flow. Here, singular solutions have recently been found for flows involving a stagnation point. These solutions appear to be the mathematical structures underlying the birefringent strands that have been observed experimentally in these flows. In this thesis, explicit approximate solutions are found for idealized extensional flow geometries and simple constitutive equations. Asymptotic results are derived for the width of the strand and other typical parameters. It appears that non-analytical solutions are a general feature of elongational viscoelastic flows, which should also occur for more realistic flows and models.UBL - phd migration 201

    On the monotone stability approach to BSDEs with jumps: Extensions, concrete criteria and examples

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    We show a concise extension of the monotone stability approach to backward stochastic differential equations (BSDEs) that are jointly driven by a Brownian motion and a random measure for jumps, which could be of infinite activity with a non-deterministic and time inhomogeneous compensator. The BSDE generator function can be non convex and needs not to satisfy global Lipschitz conditions in the jump integrand. We contribute concrete criteria, that are easy to verify, for results on existence and uniqueness of bounded solutions to BSDEs with jumps, and on comparison and a-priori LL^{\infty}-bounds. Several examples and counter examples are discussed to shed light on the scope and applicability of different assumptions, and we provide an overview of major applications in finance and optimal control.Comment: 28 pages. Added DOI https://link.springer.com/chapter/10.1007%2F978-3-030-22285-7_1 for final publication, corrected typo (missing gamma) in example 4.1

    The Effect of Entrepreneurial Marketing on Outcome Goals in SMEs

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    This study examines how entrepreneurial marketing dimensions (proactiveness, opportunity focused, leveraging, innovativeness, risk taking, value creation, and customer intensity) are related to qualitative and quantitative outcome measures for the SME and the entrepreneur (including company success, customer success, financial success, satisfaction with return goals, satisfaction with growth goals, excellence, and the entrepreneur’s standard of living). Using factor analysis, three success outcome variables (financial, customer, and strong company success) emerged together. A separate factor analysis identified satisfactory growth and return goals. Stepwise regression revealed entrepreneurial marketing impacts outcome variables, particularly value creation. Implications for entrepreneurs and areas for research are included

    Resolving the order parameter of High-Tc_{c} Superconductors through quantum pumping spectroscopy

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    The order parameter of High-Tc_{c} superconductors through a series of experiments has been quite conclusively demonstrated to not be of the normal swaves-wave type. It is either a pure dx2y2d_{x^{2}-y^{2}}-wave type or a mixture of a dx2y2waved_{x^{2}-y^{2}}-wave with a small imaginary swaves-wave or dxywaved_{xy}-wave component. In this work a distinction is brought out among the four types, i.e., swaves- wave, dx2y2waved_{x^{2}-y^{2}}- wave, dx2y2+iswaved_{x^{2}-y^{2}}+is - wave and dx2y2+idxywaved_{x^{2}-y^{2}}+id_{xy}- wave types with the help of quantum pumping spectroscopy. This involves a normal metal double barrier structure in contact with a High-Tc_{c} superconductor. The pumped current, heat and noise show different characteristics with change in order parameter revealing quite easily the differences among these.Comment: 11 pages, 3 figures, 1 table, Manuscript revised with new material on d+id' cas

    Quadratic BSDEs driven by a continuous martingale and application to utility maximization problem

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    In this paper, we study a class of quadratic Backward Stochastic Differential Equations (BSDEs) which arises naturally when studying the problem of utility maximization with portfolio constraints. We first establish existence and uniqueness results for such BSDEs and then, we give an application to the utility maximization problem. Three cases of utility functions will be discussed: the exponential, power and logarithmic ones

    The effect of the oil resin on the properties of solution of the petroleum wax treated in an ultrasonic field

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    It was found that the complex treatment of ultrasonic followed by the addition of 0.3% by weight. petroleum resins, a more efficient method of inhibiting sedimentation processes than just ultrasonic or addition of 0,3% by weight. petroleum resins. According to the obtained data, fragments of aliphatic petroleum resins are adsorbed on the high molecular hydrocarbons of normal structure and prevent their aggregation thus the inhibition of sedimentation occurs

    Microdevices for extensional rheometry of low viscosity elastic liquids : a review

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    Extensional flows and the underlying stability/instability mechanisms are of extreme relevance to the efficient operation of inkjet printing, coating processes and drug delivery systems, as well as for the generation of micro droplets. The development of an extensional rheometer to characterize the extensional properties of low viscosity fluids has therefore stimulated great interest of researchers, particularly in the last decade. Microfluidics has proven to be an extraordinary working platform and different configurations of potential extensional microrheometers have been proposed. In this review, we present an overview of several successful designs, together with a critical assessment of their capabilities and limitations

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

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    A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV
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