800 research outputs found
ERTS-1 applied for structural and morphological investigtions case studies. 1: Los Angeles, California. 2: Coastal plain, New Jersey
Two major earth's resources management problems, the application of ERTS-1 imagery for geomorphotectonics, and subsequently seismic-risk, earthquake, and mineral exploration applications are discussed. Case studies are presented for Los Angeles, California, and New Jersey coastal plain
Carbon ordering in an aseismic shear zone : implications for Raman geothermometry and strain tracking
Acknowledgements: This study was carried out as part of a University of Aberdeen PhD, supported by the NERC (Natural Environment Research Council) Centre for Doctoral Training in Oil & Gas [grant number 316 NE/R01051X/1].Peer reviewedPostprin
Non-ergodicity of the motion in three dimensional steep repelling dispersing potentials
It is demonstrated numerically that smooth three degrees of freedom
Hamiltonian systems which are arbitrarily close to three dimensional strictly
dispersing billiards (Sinai billiards) have islands of effective stability, and
hence are non-ergodic. The mechanism for creating the islands are corners of
the billiard domain.Comment: 6 pages, 8 figures, submitted to Chao
Symmetry breaking perturbations and strange attractors
The asymmetrically forced, damped Duffing oscillator is introduced as a
prototype model for analyzing the homoclinic tangle of symmetric dissipative
systems with \textit{symmetry breaking} disturbances. Even a slight fixed
asymmetry in the perturbation may cause a substantial change in the asymptotic
behavior of the system, e.g. transitions from two sided to one sided strange
attractors as the other parameters are varied. Moreover, slight asymmetries may
cause substantial asymmetries in the relative size of the basins of attraction
of the unforced nearly symmetric attracting regions. These changes seems to be
associated with homoclinic bifurcations. Numerical evidence indicates that
\textit{strange attractors} appear near curves corresponding to specific
secondary homoclinic bifurcations. These curves are found using analytical
perturbational tools
Free-space optical communication employing subcarrier modulation and spatial diversity in atmospheric turbulence channel
An expression for the bit error rate of a multiple subcarrier intensity-modulated atmospheric optical communication system employing spatial diversity is derived. Spatial diversity is used to mitigate scintillation caused by atmospheric turbulence, which is assumed to obey lognormal distribution. Optimal but complex maximum ratio, equal gain combining (EGC) and relatively simple selection combining spatial diversity techniques in a clear atmosphere are considered. Each subcarrier is modulated using binary phase shift keying. Laser irradiance is subsequently modulated by a subcarrier signal, and a direct detection PIN receiver is employed (i.e. intensity modulation/direction detection). At a subcarrier level, coherent demodulation is used to extract the transmitted data/information. The performance of onâoff-keying is also presented and compared with the subcarrier intensity modulation under the same atmospheric conditions
A New Method for Estimating Effects of Visual Field Loss in a Panoramic Driving Environment
Glaucoma is a key cause of peripheral visual field loss and increases risk of a vehicle crash. Patients may be unaware of their visual loss and of hazards in the driving panorama. Standard clinical automated perimetry, the âgold standardâ for monitoring glaucoma progression, lacks external validity to evaluate functional effect of visual field loss in driving environments. We developed and piloted a new technique to study the effects of glaucoma in a panoramic (290 forward FOV) simulated driving environment. Preliminary results in 11 drivers (7 with glaucoma and 4 with suspected glaucoma): (1) demonstrate the relationship between standard clinical perimetry and driving simulator visual fields, (2) replicate clinical evidence of glaucoma-related peripheral visual field loss, and (3) show added visual field loss due to visual occlusion by in-cab geometry
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