461 research outputs found
Stochastic simulation of non-stationary continuous multifractal time series
No full textIntermittency is an ubiquitous property of fully developed turbulence, for Eulerian and Lagrangian fields, and for velocity, passive and active scalars. Intermittency corresponds to multi-scale high fluctuations, with some underlying long-range correlations. Such property is usually characterized using scaling approaches, verified using experimental or numerical data. However there are only few studies devoted to the generation of continuous stochastic processes having non-stationary multifractal properties, able to mimic Eulerian or Lagrangian velocity or passive scalar time series. Here we review recent works on this topic, and we provide stochastic simulations in order to verify the theoretical predictions. In the lognormal framework we provide a plane expressing the scale invariant properties of these simulations
Three-component velocity measurements in a momentum-conserving, axisymmetric, turbulent jet
No full textExperiments have been performed on a momentum conserving axisymmetric turbulent jet, the turbulence characteristics of which are well known [1]. Simultaneous three-component velocity measurements are acquired with high spatial and temporal resolution, using a new triple-sensor hotwire probe. Velocity and directional calibrations are performed using a dedicated automatic calibration system. Two experiments are performed; one for capturing the average velocity field in a 3D volume, and one for investigating the turbulence spectra in specific points in space. In the first experiment, measurements are performed in 9 equidistant cross-planes, from 10- to 50-diameters downstream of the nozzle using a computer-controlled traversing system. The spatial resolution is as low as 1 mm and the sampling rate was 10 kHz. In the second experiment, long velocity time histories are acquired with 50 kHz sampling rate to perform power spectral density computations for each velocity component. Preliminary results of velocity capture confirm the general characteristics of the turbulent jet. The power spectra at different positions indicate that the turbulent fluctuations are not isotropic at lower frequencies
Joint scaling analysis of atmospheric velocity and wind power plant production
No full textIn a context of energy transition, wind energy is a source of clean energy with the potential of partially satisfying the growing demand. The main problem of this type of energy, and other types of renewable energy remains the discontinuity of the electric power produced in different scales, inducing large fluctuations also called intermittency. This intermittency of wind energy is inherent to the turbulent nature of wind. Here, we consider the relation between velocity and power output with two wind turbine databases. We focus on joint relations with Fourrier analysis, empirical mode decomposition (EMD), Time-dependent intrinsic correlation (TDIC). We also consider the causality using a new method of analysis of the causality between two time series
The entry price threshold in EU F&V sector: deterrence or effective barrier?
No full textThe paper investigates the effects of the entry price scheme for fresh fruit and vegetables. The analysis is conducted on the EU prices of tomatoes, lemons and apples for some of the main competing countries on the EU domestic markets: Morocco, Argentina, Turkey and China. The econometric analysis is based on testing and estimating a switching vector autoregressive model with endogenous threshold entry price level. The model shows the isolation effects and the accumulation of SIVs above the trigger entry price. This paper contributes to clarify the role played by the EPS in avoid or deter low priced imports from main EU partner Countries.Fruits and vegetables, Entry price system, trade policy, TVAR, Agricultural and Food Policy, F13, Q17, Q18,
A Circulating MicroRNA Profile in a Laser-Induced Mouse Model of Choroidal Neovascularization
No full textFunding: This research was funded by the Deutsche Forschungsgemeinschaft (GR5065/1-1). Author Contributions: Conceptualization, F.G. and B.H.F.W.; Data curation, T.S.; Formal analysis, P.B., M.K., A.A., and T.S.; Funding acquisition, C.K. and F.G.; Investigation, M.K. and B.H.F.W.; Methodology, C.K. and A.A.;Project administration, B.H.F.W.; Resources, M.K., A.A., T.L., and F.G.; Software, C.K. and T.S.; Supervision, T.L., F.G., and B.H.F.W.; Validation, P.B.; Visualization, C.K.; Writing—original draft, C.K. and P.B.; Writing—review & editing, B.H.F.W. All authors have read and agreed to the published version of the manuscript.Peer reviewe
(Re)organizing circular design projects: Four tool applications and reflections
No full textGreen Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Integral Design & Managemen
Superconducting flux qubits: Quantum chains and tunable qubits
No full textThis thesis presents results of theoretical and experimental work on superconducting persistent-current flux quantum bits. These qubits are promising candidates for the implementation of scalable quantum information processing. This work focuses on the study of one dimensional chains of inductively coupled flux qubits and on qubits with a tunable energy gap. Chains of flux qubits can be used as models of quantum spin chains, one of the most basic systems in many-body physics that has been extensively studied theoretically. The ability to design and tune the qubit and coupling parameters enables exploration of different phase regimes during measurements, in parameter regimes that are not accessible with magnetic materials. The study of the dynamics of quantum waves in an artificial spin chain can also be used to explore novel quantum phenomena with possible applications in quantum computing. Tunability of the minimal energy splitting (the gap) enables one to rapidly bring the flux qubit in and out of resonance with other quantum systems, including a harmonic oscillator. With tunable qubits it also becomes possible to create inter-qubit couplings of different vector nature, using magnetic fluxes. This permits the design of various interaction Hamiltonians for multiple qubit systems. These operations can be performed at the degeneracy point of the qubit, where coherence properties are optimal. Therefore the tunable flux qubit provides an attractive component for the implementation of scalable quantum computation.Kavli Institute of Nanoscience DelftApplied Science
Breaking the geometric magnetic frustration in controlled off-stoichiometric LuMn1+zO3+o compounds
No full textAccepted Author ManuscriptRST/Fundamental Aspects of Materials and Energ
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