76,413 research outputs found
Stationary and Mobile Target Detection using Mobile Wireless Sensor Networks
In this work, we study the target detection and tracking problem in mobile
sensor networks, where the performance metrics of interest are probability of
detection and tracking coverage, when the target can be stationary or mobile
and its duration is finite. We propose a physical coverage-based mobility
model, where the mobile sensor nodes move such that the overlap between the
covered areas by different mobile nodes is small. It is shown that for
stationary target scenario the proposed mobility model can achieve a desired
detection probability with a significantly lower number of mobile nodes
especially when the detection requirements are highly stringent. Similarly,
when the target is mobile the coverage-based mobility model produces a
consistently higher detection probability compared to other models under
investigation.Comment: 7 pages, 12 figures, appeared in INFOCOM 201
Numerical study of halo concentrations in dark-energy cosmologies
We study the concentration parameters, their mass dependence and redshift
evolution, of dark-matter halos in different dark-energy cosmologies with
constant and time-variable equation of state, and compare them with "standard''
Lambda-CDM and OCDM models. We find that previously proposed algorithms for
predicting halo concentrations can be well adapted to dark-energy models. When
centred on the analytically expected values, halo concentrations show a
log-normal distribution with a uniform standard deviation of ~0.2. The
dependence of averaged halo concentrations on mass and redshift permits a
simple fit of the form (1+z) c=c0 (M/M0)^a, with a~-0.1 throughout. We find
that the cluster concentration depends on the dark energy equation of state at
the cluster formation redshift z_{coll} through the linear growth factor
D_+(z_{coll}). As a simple correction accounting for dark-energy cosmologies,
we propose scaling c0 from Lambda-CDM with the ratio of linear growth factors,
c0 -> c0 D_+(z_{coll})/D_{+,Lambda-CDM}(z_{coll}).Comment: 11 pages, submitted to Astronomy & Astrophysic
Control optimization, stabilization and computer algorithms for aircraft applications
The analysis and design of complex multivariable reliable control systems are considered. High performance and fault tolerant aircraft systems are the objectives. A preliminary feasibility study of the design of a lateral control system for a VTOL aircraft that is to land on a DD963 class destroyer under high sea state conditions is provided. Progress in the following areas is summarized: (1) VTOL control system design studies; (2) robust multivariable control system synthesis; (3) adaptive control systems; (4) failure detection algorithms; and (5) fault tolerant optimal control theory
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