5,010 research outputs found
Trajectory Clustering and an Application to Airspace Monitoring
This paper presents a framework aimed at monitoring the behavior of aircraft
in a given airspace. Nominal trajectories are determined and learned using data
driven methods. Standard procedures are used by air traffic controllers (ATC)
to guide aircraft, ensure the safety of the airspace, and to maximize the
runway occupancy. Even though standard procedures are used by ATC, the control
of the aircraft remains with the pilots, leading to a large variability in the
flight patterns observed. Two methods to identify typical operations and their
variability from recorded radar tracks are presented. This knowledge base is
then used to monitor the conformance of current operations against operations
previously identified as standard. A tool called AirTrajectoryMiner is
presented, aiming at monitoring the instantaneous health of the airspace, in
real time. The airspace is "healthy" when all aircraft are flying according to
the nominal procedures. A measure of complexity is introduced, measuring the
conformance of current flight to nominal flight patterns. When an aircraft does
not conform, the complexity increases as more attention from ATC is required to
ensure a safe separation between aircraft.Comment: 15 pages, 20 figure
Near infra-red spectroscopy of V838 Monocerotis
Near IR, multi-epoch, spectroscopic and photometric observations of the
enigmatic, eruptive variable V838 Mon in JHK bands are reported. One of the
unusual features is the detection of several strong neutral TiI lines in
emission in the K band. From the strength of these lines, the mass of the
ejected envelope is estimated to be in the range 10e-7 to 10e-5 M(sun). The
spectra also show the strong presence of the first and second overtones of 12CO
bands seen in the K and H bands. The CO bands show a complex evolution. Deep
water bands at 1.4 and 1.9 micron are also seen later in the object's
evolution. Blackbody fits to the JHK photometric data show that V838 Mon has
evolved to temperatures between 2400 - 2600 K by approximately 130 days after
outburst. The spectra at this stage have the general characteristics of a very
cool M giant.Comment: 7 pages, 5 figures, to appear in Astronomy and Astrophysic
Multifunctional Magnetoelectric Materials for Device Applications
Mutiferroics are a novel class of next generation multifunctional materials,
which display simultaneous magnetic spin, electric dipole, and ferroelastic
ordering, and have drawn increasing interest due to their multi-functionality
for a variety of device applications. Since single-phase materials exist rarely
in nature with such cross-coupling properties, an intensive research activity
is being pursued towards the discovery of new single-phase multiferroic
materials and the design of new engineered materials with strong
magneto-electric (ME) coupling. This review article summarizes the development
of different kinds of multiferroic material: single-phase and composite
ceramic, laminated composite, and nanostructured thin films. Thin-film
nanostructures have higher magnitude direct ME coupling values and clear
evidence of indirect ME coupling compared with bulk materials. Promising ME
coupling coefficients have been reported in laminated composite materials in
which signal to noise ratio is good for device fabrication. We describe the
possible applications of these materials
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