20,003 research outputs found
Instrument accurately measures small temperature changes on test surface
Calorimeter apparatus accurately measures very small temperature rises on a test surface subjected to aerodynamic heating. A continuous thin sheet of a sensing material is attached to a base support plate through which a series of holes of known diameter have been drilled for attaching thermocouples to the material
Heat sensing instrument Patent
Heat sensing instrument, using thermocouple junction connected under heavy conducting materia
Gluon contributions to the pion mass and light cone momentum fraction
We calculate the matrix elements of the gluonic contributions to the
energy-momentum tensor for a pion of mass 600 < Mpi < 1100 MeV in quenched
lattice QCD. We find that gluons contribute (37 +/- 8 +/- 12)% of the pion's
light cone momentum. The bare matrix elements corresponding to the trace
anomaly contribution to the pion mass are also obtained. The discretizations of
the energy-momentum tensor we use have other promising applications, ranging
from calculating the origin of hadron spin to QCD thermodynamics.Comment: 4 pages, 2 figure
Control of supersonic wind-tunnel noise by laminarization of nozzle-wall boundary layer
One of the principal design requirements for a quiet supersonic or hypersonic wind tunnel is to maintain laminar boundary layers on the nozzle walls and thereby reduce disturbance levels in the test flow. The conditions and apparent reasons for laminar boundary layers which have been observed during previous investigations on the walls of several nozzles for exit Mach numbers from 2 to 20 are reviewed. Based on these results, an analysis and an assessment of nozzle design requirements for laminar boundary layers including low Reynolds numbers, high acceleration, suction slots, wall temperature control, wall roughness, and area suction are presented
Comparison of prediction methods and studies of relaxation in hypersonic turbulent nozzle-wall boundary layers
Turbulent boundary layer measurements on axisymmetric hypersonic nozzle wall
Simulation of the Burridge-Knopoff Model of Earthquakes with Variable Range Stress Transfer
Simple models of earthquake faults are important for understanding the
mechanisms for their observed behavior, such as Gutenberg-Richter scaling and
the relation between large and small events, which is the basis for various
forecasting methods. Although cellular automaton models have been studied
extensively in the long-range stress transfer limit, this limit has not been
studied for the Burridge-Knopoff model, which includes more realistic friction
forces and inertia. We find that the latter model with long-range stress
transfer exhibits qualitatively different behavior than both the long-range
cellular automaton models and the usual Burridge-Knopoff model with nearest
neighbor springs, depending on the nature of the velocity-weakening friction
force. This result has important implications for our understanding of
earthquakes and other driven dissipative systems.Comment: 4 pages, 5 figures, published on Phys. Rev. Let
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