10,849 research outputs found
Optimal Flood Control
A mathematical model for optimal control of the water levels in a chain of
reservoirs is studied. Some remarks regarding sensitivity with respect to the time horizon, terminal cost and forecast of inflow are made
Human behavioural analysis with self-organizing map for ambient assisted living
This paper presents a system for automatically classifying the resting location of a moving object in an indoor environment. The system uses an unsupervised neural network (Self Organising Feature Map) fully implemented on a low-cost, low-power automated home-based surveillance system, capable of monitoring activity level of elders living alone independently. The proposed system runs on an embedded platform with a specialised ceiling-mounted video sensor for intelligent activity monitoring. The system has the ability to learn resting locations, to measure overall activity levels and to detect specific events such as potential falls. First order motion information, including first order moving average smoothing, is generated from the 2D image coordinates (trajectories). A novel edge-based object detection algorithm capable of running at a reasonable speed on the embedded platform has been developed. The classification is dynamic and achieved in real-time. The dynamic classifier is achieved using a SOFM and a probabilistic model. Experimental results show less than 20% classification error, showing the robustness of our approach over others in literature with minimal power consumption. The head location of the subject is also estimated by a novel approach capable of running on any resource limited platform with power constraints
EVOLUTION OF IR-SELECTED GALAXIES IN Z~0.4 CLUSTERS
Wide-field optical and near--IR () imaging is presented for two rich
galaxy clusters: Abell~370 at and Abell~851 (Cl0939+47) at .
Galaxy catalogs selected from the near--IR images are 90\% complete to
approximately 1.5 mag below resulting in samples with 100
probable member galaxies per cluster in the central 2 Mpc. Comparison
with WFPC images yields subsamples of 70 galaxies in each cluster
with morphological types. Analysis of the complete samples and the
subsamples shows that the E/S0s are bluer than those in the Bower
et al.\ (1992) Coma sample in the optical color by ~mag for Abell~370
and by ~mag for Abell~851. If real, the bluing of the E/S0 populations at
moderate redshift is consistent with that calculated from the Bruzual and
Charlot (1993) models of passive elliptical galaxy evolution. In both clusters
the intrinsic scatter of the known E/S0s about their optical color--mag
relation is small ( mag) and not significantly different from that
of Coma E/S0s as given by Bower et al.\ (1992), indicating that the galaxies
within each cluster formed at the same time at an early epoch.Comment: uuencoded gzipped tar file containing latex files of manuscript (42
pages) plus tables (9 pages); figures available by anonymous ftp at
ftp://ipac.caltech.edu//pub/pickup/sed ; accepted for publication in the Ap
Using the local gyrokinetic code, GS2, to investigate global ITG modes in tokamaks. (I) s- model with profile and flow shear effects
This paper combines results from a local gyrokinetic code with analytical
theory to reconstruct the global eigenmode structure of the linearly unstable
ion-temperature-gradient (ITG) mode with adiabatic electrons. The simulations
presented here employ the s- tokamak equilibrium model. Local
gyrokinetic calculations, using GS2 have been performed over a range of radial
surfaces, x, and for ballooning phase angle, p, in the range -, to map out the complex local mode frequency, . Assuming a quadratic radial profile for the
drive, namely , (holding constant all other equilibrium
profiles such as safety factor, magnetic shear etc.), has a
stationary point. The reconstructed global mode then sits on the outboard mid
plane of the tokamak plasma, and is known as a conventional or isolated mode,
with global growth rate, ~ Max[], where
is the local growth rate. Taking the radial variation in
other equilibrium profiles (e.g safety factor q(x)) into account, removes the
stationary point in and results in a mode that peaks
slightly away from the outboard mid-plane with a reduced global growth rate.
Finally, the influence of flow shear has also been investigated through a
Doppler shift, , where n
is the toroidal mode number and incorporates the effect of
flow shear. The equilibrium profile variation introduces an asymmetry to the
growth rate spectrum with respect to the sign of ,
consistent with recent global gyrokinetic calculations.Comment: 10 pages, 8 figures and 1 tabl
Transition state theory and the dynamics of hard disks
The dynamics of two and five disk systems confined in a square has been
studied using molecular dynamics simulations and compared with the predictions
of transition state theory. We determine the partition functions Z and
Z^\ddagger of transition state theory using a procedure first used by Salsburg
and Wood for the pressure. Our simulations show this procedure and transition
state theory are in excellent agreement with the simulations. A generalization
of the transition state theory to the case of a large number of disks N is made
and shown to be in full agreement with simulations of disks moving in a narrow
channel. The same procedure for hard spheres in three dimensions leads to the
Vogel-Fulcher-Tammann formula for their alpha relaxation time.Comment: 1 new author, new simulations and figures, less speculation. Now 6
pages, 6 figures, 1 animation. Animation may be viewed at
http://www.theory.physics.manchester.ac.uk/~godfrey/supplement/activated_dynamics2.htm
Towards a standardised line list for G191-B2B, and other DA type objects
We present a comprehensive analysis of the far UV spectrum of G191-B2B over
the range of 900-1700{\AA} using co-added data from the FUSE and STIS archives.
While previous identifications made by Holberg et al. (2003) are reaffirmed in
this work, it is found that many previously unidentified lines can now be
attributed to Fe, Ni, and a few lighter metals. Future work includes extending
this detailed analysis to a wider range of DA objects, in the expectation that
a more complete analysis of their atmospheres can be realised.Comment: 4 pages, 2 figures, 1 table: To appear in the proceedings of the
"18th European White Dwarf Workshop" in Krakow, Poland, 201
Near-IR imaging of moderate redshift galaxy clusters
We have obtained near-IR imaging of 3 moderate-z clusters on the 1.3 m at KPNO with SQIID, a new camera offering wide-field (5.5 arcmin) simultaneous JHK band imaging. Our photometry on a sample of approximately 100 likely member galaxies in one of the clusters, Abell 370 at z = 0.37, shows that we can obtain magnitudes good to 20 percent down to K = 18, considerably below the estimated K* = 16.5 at this redshift. These data indicate that there are no systematic problems in obtaining photometry at faint levels with SQIID. With the development of larger arrays, the field is open to progress. The resulting J, H, and K data for three clusters are combined with previously obtained multiband optical photometry. We present an investigation of the spectral properties and evolution of the dominant cold stellar populations by comparing optical-to-IR colors and color-magnitude diagrams to predictions from population synthesis models and galaxy spectral evolution codes
Dorsalization of the neural tube by the non-neural ectoderm
The patterning of cell types along the dorsoventral axis of the spinal cord requires a complex set of inductive signals. While the chordamesoderm is a well-known source of ventralizing signals, relatively little is known about the cues that induce dorsal cell types, including neural crest. Here, we demonstrate that juxtaposition of the non-neural and neural ectoderm is sufficient to induce the expression of dorsal markers, Wnt-1, Wnt-3a and Slug, as well as the formation of neural crest cells. In addition, the competence of neural plate to express Wnt-1 and Wnt-3a appears to be stage dependent, occurring only when neural tissue is taken from stage 8–10 embryos but not from stage 4 embryos, regardless of the age of the non-neural ectoderm. In contrast to the induction of Wnt gene expression, neural crest cell formation and Slug expression can be induced when either stage 4 or stage 8–10 neural plates are placed in contact with the non-neural ectoderm. These data suggest that the non-neural ectoderm provides a signal (or signals) that specifies dorsal cell types within the neural tube, and that the response is dependent on the competence of the neural tissue
- …