22,747 research outputs found
Correlated Equilibria of Classical Strategic Games with Quantum Signals
Correlated equilibria are sometimes more efficient than the Nash equilibria
of a game without signals. We investigate whether the availability of quantum
signals in the context of a classical strategic game may allow the players to
achieve even better efficiency than in any correlated equilibrium with
classical signals, and find the answer to be positive.Comment: 8 pages, LaTe
Energy Loss from Reconnection with a Vortex Mesh
Experiments in superfluid 4He show that at low temperatures, energy
dissipation from moving vortices is many orders of magnitude larger than
expected from mutual friction. Here we investigate other mechanisms for energy
loss by a computational study of a vortex that moves through and reconnects
with a mesh of small vortices pinned to the container wall. We find that such
reconnections enhance energy loss from the moving vortex by a factor of up to
100 beyond that with no mesh. The enhancement occurs through two different
mechanisms, both involving the Kelvin oscillations generated along the vortex
by the reconnections. At relatively high temperatures the Kelvin waves increase
the vortex motion, leading to more energy loss through mutual friction. As the
temperature decreases, the vortex oscillations generate additional reconnection
events between the moving vortex and the wall, which decrease the energy of the
moving vortex by transfering portions of its length to the pinned mesh on the
wall.Comment: 9 pages, 10 figure
Direct Numerical Simulation of a separated channel flow with a smooth profile
A direct numerical simulation (DNS) of a channel flow with one curved surface
was performed at moderate Reynolds number (Re_tau = 395 at the inlet). The
adverse pressure gradient was obtained by a wall curvature through a
mathematical mapping from physical coordinates to Cartesian ones. The code,
using spectral spanwise and normal discretization, combines the advantage of a
good accuracy with a fast integration procedure compared to standard numerical
procedures for complex geometries. The turbulent flow slightly separates on the
profile at the lower curved wall and is at the onset of separation at the
opposite flat wall. The thin separation bubble is characterized with a reversal
flow fraction. Intense vortices are generated near the separation line on the
lower wall but also at the upper wall. Turbulent normal stresses and kinetic
energy budget are investigated along the channel.Comment: 23 pages, submitted to Journal of Turbulenc
Minimizing boundary layer bleed for a mixed compression inlet
An experimental investigation of a full scale mixed compression inlet sized for the TF30-P-3 turbofan engine was conducted at Mach 2.5 and 2.0 operating conditions. The two cone axisymmetric inlet had minimum internal contraction consistent with high total pressure recovery and low cowl drag. At Mach 2.5, inlet recovery exceeded 0.90 with only 0.02 centerbody bleed mass-flow ratio and zero cowl bleed. A centerbody bleed of approximately 0.05 gave a maximum inlet unstart angle-of-attack of 6.85 deg. Inlet performance and angle-of-attack tolerance is presented for operation at Mach 2.5 and 2.0
Distortion in a full-scale bicone inlet with internal focused compression and 45 percent internal contraction
The distortion characteristics were investigated at the subsonic diffuser exit of a full-scale, Mach 2.5, axisymmetric, mixed compression inlet. Performance and steady-state distortion characteristics were obtained at zero and maximum angle of attack and during an inlet unstart-restart sequence. For the configuration with no cowl bleed, steady-state distortion P(max)P(min)P(bar) ranged from 0.10 for critical inlet operation at 0 deg angle-of-attack to 0.306 for supercritical inlet operation at 6.84 deg angle-of-attack. Vortex generators provided a 50 percent reduction in steady-state distortion for critical operation. Bleed has a smaller effect on steady-stated distortion
Performance of vortex generators in a Mach 2.5 low-bleed full scale 45-percent-internal-contraction axisymmetric inlet
Steady-state and dynamic flow characteristics associated with two sets of vortex generators having different mixing criteria were determined. The inlet performance with and without these vortex generators is presented. The vortex generators were successful in eliminating separation, increasing area-weighted total pressure recovery, and decreasing distortion. Transmission times obtained from cross-correlations of the wall static pressures and the diffuser exit total pressure showed no effect of the upstream flow characteristics on the diffuser exit pressures when generators were used. Without generators, separation occurred and the upstream pressure characteristics had immediate effects on the diffuser exit pressure characteristics
Holographic quantum states
We show how continuous matrix product states of quantum field theories can be
described in terms of the dissipative non-equilibrium dynamics of a
lower-dimensional auxiliary boundary field theory. We demonstrate that the
spatial correlation functions of the bulk field can be brought into one-to-one
correspondence with the temporal statistics of the quantum jumps of the
boundary field. This equivalence: (1) illustrates an intimate connection
between the theory of continuous quantum measurement and quantum field theory;
(2) gives an explicit construction of the boundary field theory allowing the
extension of real-space renormalization group methods to arbitrary dimensional
quantum field theories without the introduction of a lattice parameter; and (3)
yields a novel interpretation of recent cavity QED experiments in terms of
quantum field theory, and hence paves the way toward observing genuine quantum
phase transitions in such zero-dimensional driven quantum systems.Comment: 6 pages, 1 figure. Emphasis change
Boundary layer bleed system study for a full-scale, mixed-compression inlet with 45 percent internal contraction
The results of an experimental bleed development study for a full-scale, Mach 2.5, axisymmetric, mixed-compression inlet were presented. The inlet was designed to satisfy the airflow requirements of the TF30-P-3 turbofan engine. Capabilities for porous bleed on the cowl surface and ram-scoop/flush-slot bleed on the centerbody were provided. A configuration with no bleed on the cowl achieved a minimum stable, diffuser exit, total pressure recovery of 0.894 with a centerbody-bleed mass flow ratio of 0.02. Configurations with cowl bleed had minimum stable recoveries as high as 0.900 but suffered range decrement penalties from the increased bleed mass flow removal. Limited inlet stability and unstart angle-of-attack data are presented
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