96,349 research outputs found
Internal report cluster 1: Urban freight innovations and solutions for sustainable deliveries (1/4)
Technical report about sustainable urban freight solutions, part 1 of
Evaluation capabilities for transient pressure transducers Summary report
Evaluation capabilities for transient pressure transducer
A simple method of calculating power-law velocity profile exponents from experimental data
Analytical expressions for the effects of compressibility and heat transfer on laminar and turbulent shape factors H have been developed. Solving the turbulent equation for the power law velocity profile exponent N has resulted in a simple technique by which the N values of experimental turbulent profiles can be calculated directly from the integral parameters. Thus the data plotting, curve fitting, and slope measuring, which is the normal technique of obtaining experimental N values, is eliminated. The N values obtained by this method should be within the accuracy with which they could be measured
Effects of Mach number on pitot-probe displacement in a turbulent boundary layer
Experimental pitot-probe-displacement data have been obtained in a turbulent boundary layer at a local free-stream Mach number of 4.63 and unit Reynolds number of 6.46 million meter. The results of this study were compared with lower Mach number results of previous studies. It was found that small probes showed displacement only, whereas the larger probes showed not only displacement but also distortion of the shape of the boundary-layer profile. The distortion pattern occurred lower in the boundary layer at the higher Mach number than at the the lower Mach number. The maximum distortion occurred when the center of the probe was about one probe diameter off the test surface. For probes in the wall contact position, the indicated Mach numbers were, for all probes tested, close to the true profile. Pitot-probe displacement was found to increase significantly with increasing Mach number
Reevaluation of compressible-flow Preston tube calibrations
Revised zero-pressure-gradient, adiabatic wall skin-friction-balance data covering a Mach number range from 1.6 to 4.6 led to a reevaluation of existing compressible flow Preston tube calibration equations
Experimental Preston tube and law-of-the-wall study of turbulent skin friction on axisymmetric bodies at supersonic speeds
Experimental Preston tube and law-of-the-wall study of turbulent skin friction on axisymmetric bodies at supersonic speed
Computing the local pressure in molecular dynamics simulations
Computer simulations of inhomogeneous soft matter systems often require
accurate methods for computing the local pressure. We present a simple
derivation, based on the virial relation, of two equivalent expressions for the
local (atomistic) pressure in a molecular dynamics simulation. One of these
expressions, previously derived by other authors via a different route,
involves summation over interactions between particles within the region of
interest; the other involves summation over interactions across the boundary of
the region of interest. We illustrate our derivation using simulations of a
simple osmotic system; both expressions produce accurate results even when the
region of interest over which the pressure is measured is very small.Comment: 11 pages, 4 figure
An assessment of the newest magnetar-SNR associations
Anomalous X-ray Pulsars and Soft-Gamma Repeaters groups are magnetar
candidates featuring low characteristic ages ().
At least some of them they should still be associated with the remnants of the
explosive events in which they were born, giving clues to the type of events
leading to their birth and the physics behind the apparent high value of the
magnetar magnetic fields. To explain the high values of , a self-consistent
picture of field growth also suggests that energy injection into the SNR is
large and unavoidable, in contrast with the evolution of {\it conventional}
SNR. This modified dynamics, in turn, has important implications for the
proposed associations. We show that this scenario yields low ages for the new
candidates CXOU J171405.7-381031/CTB 37B and XMMU J173203.3-344518/G353.6-0.7,
and predicted values agree with recently found , giving support to
the overall picture.Comment: Contributed talk to the ASTRONS 2010 Conference, Cesme, Turkey, Aug.
2-6 201
Increase urban freight efficiency with delivery and servicing plan: status, methods and UK cases
Spin transport in coupled spinor Bose gases
We report direct measurements of spin transport in a trapped, partially
condensed spinor Bose gas. Detailed analyses of spin flux in this
out-of-equilibrium quantum gas are performed by monitoring the flow of atoms in
different hyperfine spin states. The main mechanisms for motion in this system
are exchange scattering and potential energy inhomogeneity, which lead to spin
waves in the normal component and domain formation in the condensate. We find a
large discrepancy in domain formation timescales with those predicted by
potential-driven formation, indicating strong coupling of the condensate to the
normal component spin wave
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