1,258 research outputs found
The non dissipative damping of the Rabi oscillations as a "which-path" information
Rabi oscillations may be viewed as an interference phenomenon due to a
coherent superposition of different quantum paths, like in the Young's two-slit
experiment. The inclusion of the atomic external variables causes a non
dissipative damping of the Rabi oscillations. More generally, the atomic
translational dynamics induces damping in the correlation functions which
describe non classical behaviors of the field and internal atomic variables,
leading to the separability of these two subsystems. We discuss on the
possibility of interpreting this intrinsic decoherence as a "which-way"
information effect and we apply to this case a quantitative analysis of the
complementarity relation as introduced by Englert [Phys. Rev. Lett.
\textbf{77}, 2154 (1996)].Comment: 5 pages, 2 figure
Passive flow control study in a convoluted intake using Stereo Particle Image Velocimetry
The ability of vortex generators (VG) to reduce the unsteady distortion at the exit plane of an S-duct (AIP) is investigated. The 3 components of the velocity at the AIP were measured using a Stereo Particle Velocimetry system with high spatial resolution. This enabled an assessment of the synchronous swirl distortion at the duct exit. A total of nine VG cases have been investigated with a systematic variation of key design variables. Overall the VGs change the duct secondary flows and separation and are able to substantially restructure the flow field at the AIP. The pressure distortion could be reduced up to 50% and a reduction in pressure loss of 30% was achieved for the mean flow field. The VGs have a substantial influence on the unsteadiness of the flow field with a reduction in peak swirl unsteadiness of 61% and an overall reduction of unsteady swirl distortion of 67%. They also suppress the primary unsteady flow switching mechanism of the datum configuration which is associated with the oscillation of bulk and twin swirl regimes. Consequently, extreme events which leads to high swirl intensity are suppressed which lower by 45% the maximum swirl intensity for the VG cases
Controllability indices for structured systems
AbstractA new methodology is proposed for the characterization of the controllability indices of linear multivariable systems. Related to the state space representation, a new symbolism dealing only with numbers associated with the position of nonnull terms of matrices is proposed. This symbolism, associated with the graphical digraph representation model, allows one to highlight, from a structural point of view, a list of dimensions of controllable subspaces corresponding one to one with the list of controllability indices
Dynamic flow distortion investigation in an S-duct using DDES and SPIV data
The dynamic flow distortion generated within convoluted aero-engine intakes can affect the performance and operability of the engine. There is a need for a better understanding of the main flow mechanisms which promote flow distortion at the exit of S-shaped intakes. This paper presents a detailed analysis of the main coherent structures in an S-duct flow field based on a Delayed Detached Eddy Simulation (DDES). The DDES capability to capture the characteristics of the highly unsteady flow field is demonstrated against high resolution, synchronous Stereoscopic Particle Image Velocimetry (SPIV) measurements at the Aerodynamic Interface Plane (AIP). The flow field mechanisms responsible for the main AIP perturbations are identified. Clockwise and counter-clockwise stream-wise vortices are alternately generated around the separation region at a frequency of St=0.53, which promotes the swirl switching at the AIP. Spanwise vortices are also shed from the separation region at a frequency of St=1.06, and convect downstream along the separated centreline shear layer. This results in a vertical modulation of the main loss region and a fluctuation of the velocity gradient between the high and low velocity flow at the AIP
Pre-equilibrium dileptons look thermal
The dilepton mass distribution from pre-equilibrium matter in
ultrarelativistic nuclear collisions is indistinguishable from a thermally
produced distribution.Comment: CERN-TH.6813/93, 3 pages (latex) plus 1 figure (uuencoded postscript
file
Storage Device Sizing for a Hybrid Railway Traction System by Means of Bicausal Bond Graphs
In this paper, the application of bicausal bond graphs for system design in electrical engineering is emphasized. In particular, it is shown how this approach is very useful for model inversion and parameter dimensioning. To illustrate these issues, a hybrid railway traction device is considered as a case study. The synthesis of a storage device (a supercapacitor) included in this system is then discussed
EP-1879: Difference between PET and RMI fusion on delineation variability for liver metastases
Rupture ductile d'un acier haute résistance X100 pour transport de gaz naturel : caractérisation et simulation
International audienceCette étude concerne la dechirure ductile d'un acier a haute limite d'élasticite utilise pour la construction des gazoducs. Le comportement anisotrope du matériau est caractérisé par des essais sur eprouvettes de traction lisse suivant trois directions principales et sur éprouvettes axisymetriques entaillées. La ténacite et la résilience sont determinéees sur des éprouvettes CT(05T) et Charpy V. L'acier étudié possède une bonne ténacité. L'objectif de l'étude est d'établir un modele de comportement et d'endommagement pour décrire la déformation et la rupture du materiau. Une extension du modèle Gurson-Tvergaard-Needleman (GTN) à l'anisotropie est utilisée. Les paramètres du modele sont ajustés sur les eprouvettes de laboratoire. La transférabilitée sur les grandes plaques en pleine épaisseur est verifiee. La propagation de dechirure ductile sur de grandes distances (plus de 100mm) est simulée
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