56,235 research outputs found
Phase-Coded FMCW PARSAX Radar Dataset
No full textDataset collected with the TU Delft PARSAX S-band coherent radar using the frequency-modulated continuous-wave (FMCW) and Phase-coded FMCW waveforms. This dataset accompanies the PhD dissertation of Utku Kumbul entitled: "Phase-coded FMCW for automotive radars".
More details about the PARSAX radar used in the measurements can be seen in: O. A. Krasnov, L. P. Ligthart, Zhijian Li, P. Lys and F. van der Zwan, "The PARSAX - full polarimetric FMCW radar with dual-orthogonal signals," 2008 European Radar Conference, 2008, pp. 84-87.
Referencing the dataset
Kumbul, Utku; Petrov, Nikita; van der Zwan, Fred (2022): Phase-Coded FMCW PARSAX Radar Dataset. 4TU.ResearchData. Dataset. https://doi.org/10.4121/21688928
@misc{Kumbul2022,
author = "Utku Kumbul and Nikita Petrov and Fred van der Zwan",
title = "{Phase-Coded FMCW PARSAX Radar Dataset}",
year = "2022",
month = "Dec",
url = "",
doi = "10.4121/21688928 " }
Paper references are:
U. Kumbul, N. Petrov, F. van der Zwan, C. S. Vaucher and A. Yarovoy, "Experimental Investigation of Phase Coded FMCW for Sensing and Communications," 2021 15th European Conference on Antennas and Propagation (EuCAP), 2021, pp. 1-5, doi: 10.23919/EuCAP51087.2021.9411464.
U. Kumbul, N. Petrov, C. S. Vaucher and A. Yarovoy, "Receiver Structures for Phase Modulated FMCW Radars," 2022 16th European Conference on Antennas and Propagation (EuCAP), 2022, pp. 1-5, doi: 10.23919/EuCAP53622.2022.9769268.
U. Kumbul, N. Petrov, C. S. Vaucher and A. Yarovoy, "Smoothed Phase-Coded FMCW: Waveform Properties and Transceiver Architecture," in IEEE Transactions on Aerospace and Electronic Systems, 2022, doi: 10.1109/TAES.2022.3206173. </p
A Dynamic Subfilter-scale Stress Model for Large Eddy Simulations Based on Physical Flow Scales
No full textWe propose a new definition of the length scale in an eddy-viscosity model for large-eddy simulations (LES). This formulation extends and generalizes a previous proposal [Piomelli, Rouhi and Geurts, Proc. ETMM10, 2014], in which the LES length scale was expressed in terms of the integral length-scale of turbulence determined by the flow characteristics and explicitly decoupled from the simulation grid; this approach was named Integral Length-Scale Approximation (ILSA). As in the original ILSA, the model coefficient was determined by the user, and required to maintain a desired contribution of the unresolved, subfilter scales (SFS) to the global transport. We propose a local formulation (local ILSA) in which the model coefficient is local in space, allowing a precise control over SFS activity as a function of location. This new formulation preserves the properties of the global model; application to channel flow and backward-facing step verifies its features and accuracy
Large-eddy simulation of a separated flow with a sub-filter scale model based on the integral length-scale
No full textA new sub-filter scale model for large-eddy simulations, which uses a length-scale proportional to the integral scale of the turbulence instead of the grid resolution to parametrize the modelled stresses, will be assessed in the prediction of the flow of a boundary-layer over a rough surface, which includes separation and reattachment
Near Wall PIV-Measurements on the Windward Slope of a Hill
No full textThe turbulent flow over periodic hills was measured near to the wall, using planar Particle-Image-Velocimetry (PIV) at high spatial resolution. Our focus is on the near wall turbulence structure on the windward slope of the hill. For large-eddy simulation (LES) we suspect that, if this was not predicted accurately, it affects the prediction of the velocity profiles over the hill crest which in turn will affect the recirculation length downstream of the hill. Regarding the time averaged velocities, we were able to resolve the linear viscous region of the boundary layer. The velocity distribution and also the Reynolds stress does not comply with the law of the wall as it is valid for a turbulent boundary layer at equilibrium
Energy dissipation and flux laws for unsteady turbulence
No full textDirect Numerical Simulations of spatially periodic unsteady turbulence show that the high Reynolds number scalings of the instantaneous energy dissipation rate and interscale energy flux at intermediate wavenumbers are qualitatively different from the well-known cornerstone scalings of equilibrium turbulence where and are time-dependent rms velocity and integral length-scales. Instead, they both scale as where and are length and velocity scales characterizing initial/overall unsteady turbulence conditions
Direct numerical simulation of turbulent Couette-Poiseuille flow with zero skin friction
No full textThe near-wall scaling of mean velocity U(y) is addressed for the case of zero skin friction on one wall of a fully turbulent channel flow. The present DNS results can be added to the evidence in support of the conjecture that U is proportional to √yw in the region just above the wall at which the mean shear dU/dy = 0
CADASIL syndrome in a large Turkish kindred caused by the R90C mutation in the Notch3 receptor
No full textMutations in the Notch3 gene are the cause of the autosomal dominant disorder CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy). The CADASIL is an adult-onset neurologic disorder (average age of onset is 45 years) characterized by recurrent strokes and dementia. Clinical features combined with cerebral magnetic resonance imaging (MRI), showing a diffuse leukoencephalopathy with subcortical infarcts in the basal ganglia and white matter, are highly contributive to the diagnosis. We present a Turkish family with CADASIL, in which 12 individuals in four generations were affected showing the typical clinical features of recurrent strokes. Mutation analysis of the Notch3 receptor gene identified the recently described R90C mutation in the N-terminal part of the gene in affected individuals. Interestingly, migraine without aura was found as an initial symptom of the disease in two young mutation carriers (22 and 25 years, respectively), who did not show any additional clinical features or any MRI abnormalities. This indicates that migraine without aura in the absence of MRI abnormalities may represent an early initial symptom of CADASIL, which is difficult to diagnose in the absence of molecular diagnosis. Therefore, the used molecular screening method for Notch3 mutations provides a rapid and accurate diagnostic tool in addition to the standard diagnostic procedures
Real-space Manifestations of Bottlenecks in Turbulence Spectra
No full textAn energy-spectrum bottleneck, a bump in the turbulence spectrum between the inertial and dissipation ranges, is shown to occur in the non-turbulent, one-dimensional, hyperviscous Burgers equation and found to be the Fourier-space signature of oscillations in the real-space velocity, which are explained by boundary-layer-expansion techniques. Pseudospectral simulations are used to show that such oscillations occur in velocity correlation functions in one- and three-dimensional hyperviscous hydrodynamical equations that display genuine turbulence
Braid Entropy of Faraday Waves driven 2D Turbulence
No full textWe report new experimental results that use tools from braid theory to characterize two-dimensional turbulent flows driven by Faraday waves. The average topological length of the material fluid lines is found to grow exponentially with time. It allows us to compute the braid’s topological entropy SBraid. We show that SBraid increases as the square root of the turbulence kinetic energy E ~ u^2, where u^2 is the horizontal velocity variance . At long times, the PDFs of Lbraid are positively skewed and present strong exponential tails
Mean flow generation by Görtler Vortices in a rotating annulus with librating side walls
No full textLongitudinal libration of the cylinder side walls of a rotating annulus in the supercritical regime induces a centrifugally unstable Stokes boundary layer which generates Görtler vortices only in a portion of a libration cycle. We show for the first time that these vortices propagate into the fluid bulk and generate an azimuthal mean flow which is retrograde (prograde) over the outer (inner) cylinder side wall. Direct numerical simulations (DNS) are carried out and Reynolds-averaged equations and kinetic energy budget of mean and fluctuating flow are used as diagnostic equations to discuss the generation mechanism and scaling behavior of the azimuthal mean flow in the fluid bulk
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