3,008 research outputs found
A non-linear observer for unsteady three-dimensional flows
A method is proposed to estimate the velocity field of an unsteady flow using
a limited number of flow measurements. The method is based on a non-linear
low-dimensional model of the flow and on expanding the velocity field in terms
of empirical basis functions. The main idea is to impose that the coefficients
of the modal expansion of the velocity field give the best approximation to the
available measurements and that at the same time they satisfy as close as
possible the non-linear low-order model. The practical use may range from
feedback flow control to monitoring of the flow in non-accessible regions. The
proposed technique is applied to the flow around a confined square cylinder,
both in two- and three-dimensional laminar flow regimes. Comparisons are
provided. with existing linear and non-linear estimation techniques
An Overview of Flow Features and Mixing in Micro T and Arrow Mixers
An overview of the mixing performances of micro T mixers operating with a single fluid is presented. The focus is on the relationship between the flow features and mixing. Indeed, T mixers are characterized by a variety of regimes for increasing Reynolds numbers; they are briefly described, in particular in terms of the three-dimensional vorticity field, which can explain the different mixing performances. The effects of changes in the aspect ratio of the channels are also reviewed. The role of instability and sensitivity analyses in highlighting the mechanisms of the onsets of the different regimes is then described. These analyses also suggest possible geometrical modifications to promote mixing. We focus on that consisting of the downward tilting of the inlet channels (arrow mixers). Arrow mixers are interesting because the onset of the engulfment regime is anticipated at lower Reynolds numbers. Hence, the mixing performances of arrow mixers with varying Reynolds number are described
Optimization of RPCs read-out panel with electromagnetic simulation
With the upgrade of the RPCs [1]-[2] and the increase of its performances,
the study and the optimization of the read-out panel is necessary in order to
maintain the signal integrity and to reduce the intrinsic crosstalk. Through
Electromagnetic Simulation, performed with CST Studio Suite, new panels design
are tested and their crosstalk property are studied. The behavior of different
type of panel is shown, in particular a panel with the decoupling strip
connected through their characteristic impedance to the ground plane is
simulated
Ageing test of the ATLAS RPCs at X5-GIF
An ageing test of three ATLAS production RPC stations is in course at X5-GIF,
the CERN irradiation facility. The chamber efficiencies are monitored using
cosmic rays triggered by a scintillator hodoscope. Higher statistics
measurements are made when the X5 muon beam is available. We report here the
measurements of the efficiency versus operating voltage at different source
intensities, up to a maximum counting rate of about 700Hz/cm^2. We describe the
performance of the chambers during the test up to an overall ageing of 4 ATLAS
equivalent years corresponding to an integrated charge of 0.12C/cm^2, including
a safety factor of 5.Comment: 4 pages. Presented at the VII Workshop on Resistive Plate Chambers
and Related Detectors; Clermont-Ferrand October 20th-22nd, 200
Evaluation of the imaging performance of the TECNOMUSE muon tomograph and its feasibility in a real scenario
Muon tomography is a very promising imaging technique for the control of cargo
containers. It takes advantage of cosmic muons and their interaction mechanisms to reconstruct
images of the volume traversed by these particles. In the present work, the imaging
performance of a novelmuon tomography scanner based on resistive plate chambers detectors
is investigated. By means of several Monte Carlo simulations, some imaging parameters are
evaluated. The results in terms of spatial resolution, field-of-view and volume and material
recognition make the presented scanner and its geometry suitable for muon tomograph
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