71,549 research outputs found
Traffic control system and method
Frequency of carrier received by aircraft is measured and compared with reference to indicate magnitude of Doppler shift. One Doppler frequency range is selected and indicated by digital signal. Difference between frequency is offset of apparent carrier frequency transmitted by aircraft
Traffic control system and method Patent
Traffic control system for supersonic transports using synchronous satellite for data relay between vehicles and ground statio
Non-equilibrium dynamics of an active colloidal "chucker"
We report Monte Carlo simulations of the dynamics of a "chucker": a colloidal
particle which emits smaller solute particles from its surface, isotropically
and at a constant rate k_c. We find that the diffusion constant of the chucker
increases for small k_c, as recently predicted theoretically. At large k_c the
chucker diffuses more slowly due to crowding effects. We compare our simulation
results to those of a "point particle" Langevin dynamics scheme in which the
solute concentration field is calculated analytically, and in which
hydrodynamic effects can be included albeit in an approximate way. By
simulating the dragging of a chucker, we obtain an estimate of its apparent
mobility coefficient which violates the fluctuation-dissipation theorem. We
also characterise the probability density profile for a chucker which sediments
onto a surface which either repels or absorbs the solute particles, and find
that the steady state distributions are very different in the two cases. Our
simulations are inspired by the biological example of
exopolysaccharide-producing bacteria, as well as by recent experimental,
simulation and theoretical work on phoretic colloidal "swimmers".Comment: re-submission after referee's comment
Programming for energy monitoring/display system in multicolor lidar system research
The Z80 microprocessor based computer program that directs and controls the operation of the six channel energy monitoring/display system that is a part of the NASA Multipurpose Airborne Differential Absorption Lidar (DIAL) system is described. The program is written in the Z80 assembly language and is located on EPROM memories. All source and assembled listings of the main program, five subroutines, and two service routines along with flow charts and memory maps are included. A combinational block diagram shows the interfacing (including port addresses) between the six power sensors, displays, front panel controls, the main general purpose minicomputer, and this dedicated microcomputer system
Using rewards and penalties to obtain desired subject performance
Operant conditioning procedures, specifically the use of negative reinforcement, in achieving stable learning behavior is described. The critical tracking test (CTT) a method of detecting human operator impairment was tested. A pass level is set for each subject, based on that subject's asymptotic skill level while sober. It is critical that complete training take place before the individualized pass level is set in order that the impairment can be detected. The results provide a more general basis for the application of reward/penalty structures in manual control research
Chandra observations of the galaxy cluster Abell 1835
We present the analysis of 30 ksec of Chandra observations of the galaxy
cluster Abell 1835. Overall, the X-ray image shows a relaxed morphology,
although we detect substructure in in the inner 30 kpc radius. Spectral
analysis shows a steep drop in the X-ray gas temperature from ~12 keV in the
outer regions of the cluster to ~4 keV in the core. The Chandra data provide
tight constraints on the gravitational potential of the cluster which can be
parameterized by a Navarro, Frenk & White (1997) model. The X-ray data allow us
to measure the X-ray gas mass fraction as a function of radius, leading to a
determination of the cosmic matter density of \Omega_m=0.40+-0.09 h_50^-0.5.
The projected mass within a radius of ~150 kpc implied by the presence of
gravitationally lensed arcs in the cluster is in good agreement with the mass
models preferred by the Chandra data. We find a radiative cooling time of the
X-ray gas in the centre of Abell 1835 of about 3x10^8 yr. Cooling flow model
fits to the Chandra spectrum and a deprojection analysis of the Chandra image
both indicate the presence of a young cooling flow (~6x10^8 yr) with an
integrated mass deposition rate of 230^+80_-50 M_o yr^-1 within a radius of 30
kpc. We discuss the implications of our results in the light of recent RGS
observations of Abell 1835 with XMM-Newton.Comment: 15 pages, 15 figures, accepted by MNRA
- …