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Broersen, P.M.T. (author)Vector time series analysis takes the same model order and model type for the different signals involved. Selection criteria have been developed to select the best order to simultaneously predict the different components of the vector. The prediction of single channels might require a different order or type for the best accuracy of each...journal article 2009
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Haverkort, J.W. (author), Kenjeres, S. (author), Kleijn, C.R. (author)The manipulation of magnetic particles in a continuous flow with magnetic fields is central to several biomedical applications, including magnetic cell separation and magnetic drug targeting. A simplified twodimensional (2D) equation describing the motion of particles in a planar Poiseuille flow is considered for various magnetic field...journal article 2009
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Broersen, P.M.T. (author)The Yule-Walker (YW) method for autoregressive (AR) estimation uses lagged-product (LP) autocorrelation estimates to compute an AR parametric spectral model. The LP estimates only have a small triangular bias in the estimated autocorrelation function and are asymptotically unbiased. However, using them in finite samples with the YW method for AR...journal article 2009
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Broersen, P.M.T. (author)The use of time series models for irregular data requires resampling of the data on an equidistant grid. Slotted resampling transforms an irregular randomly sampled process into an equidistant signal where data are missing. An approximate maximum-likelihood time series estimator has been developed to estimate the power spectral density and the...journal article 2009
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Broersen, P.M.T. (author)Spectra with narrow valleys can accurately be described with moving-average (MA) models by using only a small number of parameters. Durbin's MA method uses the estimated parameters of a long autoregressive (AR) model to calculate the MA parameters. Probably all the pejorative remarks on the quality of Durbin's method in the literature are based...journal article 2009
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Broersen, P.M.T. (author)Several algorithms for the spectral analysis of irregularly sampled random processes can estimate the spectral density for a low frequency range. A new time-series method extended that frequency range with a factor of thousand or more. The new algorithm has two requirements to give useful results. First, at least ten closest pairs of neighboring...journal article 2009
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Heus, T. (author), Jonker, H.J.J. (author), Van den Akker, H.E.A. (author), Griffith, E.J. (author), Koutek, M. (author), Post, F.H. (author)In this study, a new method is developed to investigate the entire life cycle of shallow cumuli in large eddy simulations. Although trained observers have no problem in distinguishing the different life stages of a cloud, this process proves difficult to automate, because cloud-splitting and cloud-merging events complicate the distinction...journal article 2009
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Kenjeres, S. (author), Verdoold, J. (author), Tummers, M.J. (author), Hanjalic, K. (author), Kleijn, C.R. (author)The paper reports on numerical and experimental investigations of electromagnetically driven vortical flows of an electrically conductive fluid in a generic setup. Two different configurations of permanent magnets are considered: a 3-magnet configuration in which the resulting Lorentz force is focused in the wall-boundary layers, and a 2-magnet...journal article 2009
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Kenjeres, S. (author), Hanjalic, K. (author)This article reviews some recent applications of the transient-Reynoldsaveraged Navier–Stokes (T-RANS) approach in simulating complex turbulent flows dominated by externally imposed body forces, primarily by thermal buoyancy and the Lorentz force. The T-RANS aims at numerical resolving unsteady (semi-) deterministic vortical structures in flows...journal article 2009
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Hanjalic, K. (author), Kenjeres, S. (author), Tummers, M.J. (author), Jonker, H.J.J. (author)These lecture notes contain the course material Advanced Physical Transport Phenomena, offered in the Master’s programme in Applied Physics at Delft University of Technology. The notes follow in part the concept and content of the book Fysische Transportverschijnselen II (in Dutch) by Hoogendoorn and Van der Meer (Delft University Press, 1991)....book 2009
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Kenjeres, S. (author)We performed large eddy simulations (LES) of the turbulent natural convection of an electrically conductive fluid (water with 7% Na2SO4 electrolyte solution) in a moderate (4:4:1) aspect ratio enclosure heated from below and cooled from above and subjected to external nonuniformly distributed electromagnetic fields. Different configurations with...journal article 2008
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Gillissen, J.J.J. (author)Polymer-induced drag reduction is the phenomenon by which the friction factor of a turbulent flow is reduced by the addition of small amounts of high-molecular-weight linear polymers, which conformation in solution at rest can vary between randomly coiled and rodlike. It is well known that drag reduction is positively correlated to viscous...journal article 2008
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Mortensen, P.H. (author), Andersson, H.I. (author), Gillissen, J.J.J. (author), Boersma, B.J. (author)The dynamical behavior of tiny elongated particles in a directly simulated turbulent flow field is investigated. The ellipsoidal particles are affected both by inertia and hydrodynamic forces and torques. The time evolution of the particle orientation and translational and rotational motions in a statistically steady channel flow is obtained for...journal article 2008
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Joint Scalar versus Joint Velocity-Scalar PDF Simulations of Bluff-Body Stabilized Flames with REDIMMerci, B. (author), Naud, B. (author), Roekaerts, D. (author), Maas, U. (author)Two transported PDF strategies, joint velocity-scalar PDF (JVSPDF) and joint scalar PDF (JSPDF), are investigated for bluff-body stabilized jet-type turbulent diffusion flames with a variable degree of turbulence–chemistry interaction. Chemistry is modeled by means of the novel reaction-diffusion manifold (REDIM) technique. A detailed chemistry...journal article 2008
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Van de Wiel, B.J.H. (author), Moene, A.F. (author), De Ronde, W.H. (author), Jonker, H.J.J. (author)In stably stratified flows vertical movement of eddies is limited by the fact that kinetic energy is converted into potential energy, leading to a buoyancy displacement scale z B . Our new mixing-length concept for turbulent transport in the stable boundary layer follows a rigid-wall analogy, in the sense that we assume that the buoyancy length...journal article 2008
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Sobera, M.P. (author), Kleijn, C.R. (author)We study flow and heat transfer to a cylinder in cross flow at Re = 3,900–80,000 by means of three-dimensional transient RANS (T-RANS) simulations, employing an RNG k???? turbulence model. Both the case of a bare solid cylinder and that of a solid cylinder surrounded at some fixed distance by a thin porous layer have been studied. The latter...journal article 2008
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Kenjeres, S. (author)The paper reports on a comprehensive mathematical model for simulations of blood flow under the presence of strong non-uniform magnetic fields. The model consists of a set of Navier–Stokes equations accounting for the Lorentz and magnetisation forces, and a simplified set of Maxwell’s equations (Biot–Savart/Ampere’s law) for treating the imposed...journal article 2008
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Jonker, H.J.J. (author), Heus, T. (author), Sullivan, P.P. (author)The purpose of this letter is to show that the traditional view of transport by shallow cumulus clouds needs important refinement. On the basis of a straightforward geometrical analysis of Large Eddy Simulation results of shallow cumulus clouds, we conclude (1) that the upward mass transport by clouds is strongly dominated by regions close to...journal article 2008
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- Van Reeuwijk, M. (author), Jonker, H.J.J. (author), Hanjali?, K. (author) journal article 2008
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- Van Reeuwijk, M. (author), Jonker, H.J.J. (author), Hanjali?, K. (author) journal article 2008