38,193 research outputs found
Mapping islands, reefs and shoals in the oceans surrounding Australia
The author has identified the following significant results. Comparisons of the imagery with aerial photography of areas of reefs and island and with 1:250,000 maps of coastlines indicate that the MSS imagery depicts detail to an extent which is satisfactory for 1:250,000 mapping. As the imagery does not have some of the disadvantages of aerial photography, the former should be valuable for mapping reefs, islands, and shoals. The water discoloration problem is significant as the discolored water appears to occur near shallow depths, so that confusion could arise through the misinterpretation of discolored water, when it exists, as shallow water
Mapping islands, reefs and shoals in the oceans surrounding Australia
The author has identified the following significant results. Two geometric distortion tests of the same scene using different ground control identification methods have produced different estimates of the magnitude of geometric distortions of the image frame. A comparison of imagery with hydrographic charts shows that the imagery displays shoals and reefs which are close to the water surface. Such information can be used during the compilation of new maps of such regions, in the checking of existing hydrographic charts, or for navigation warning
Recommended from our members
Taxonomy Of Thermopsis (Fabaceae) In North-America
Comprehensive reevaluation of both herbarium specimens and field observations of the North American Thermopsis leads to our recognition of 10 species. Three species occur in the southern Appalachians: T. villosa, T. mollis, and T. fraxinifolia. The Rocky Mountains and intermountain regions are populated by the relatively variable and widespread species T. divaricarpa, T. montana, and T. rhombifolia. The Pacific coastal mountains of California are dominated by the variable T. californica (with three infraspecific taxa), which gives way to T. gracilis in northern California and western Oregon. Thermopsis macrophylla and T. robusta have restricted ranges in California.Integrative Biolog
A Machian Model of Dark Energy
Einstein believed that Mach's principle should play a major role in finding a
meaningful spacetime geometry, though it was discovered later that his field
equations gave some solutions which were not Machian. It is shown, in this
essay, that the kinematical models, which are invoked to solve the
cosmological constant problem, are in fact consistent with Mach's ideas. One
particular model in this category is described which results from the
microstructure of spacetime and seems to explain the current observations
successfully and also has some benefits over the conventional models. This
forces one to think whether the Mach's ideas and the cosmological constant are
interrelated in some way.Comment: Received an Honorable mention in the Essay Contest-2002 sponsored by
the Gravity Research Foundation; A paragraph added on how the model can
explain the CMB anisotropy observations; To appear in the Classical and
Quantum Gravit
The environmental "trade balance" between Scotland and the rest of the UK : an inter-regional input-output and SAM analysis
We use an inter-regional input-output (IO) and social accounting matrix (SAM) pollution attribution framework to serve as a platform for sub-national environmental attribution and trade balance analysis. While the existence of significant data problems mean that the quantitative results of this study should be regarded as provisional, the inter-regional economy-environment IO and SAM framework for Scotland and the rest of the UK (RUK) allows an illustrative analysis of some very important issues. There are two key findings. The first is that there are large environmental spillovers between the regions of the UK. This has implications in terms of the devolution of responsibility for achieving targets for reductions in emissions levels and the need for policy co-ordination between the UK national and devolved governments. The second finding is that whilst Scotland runs an economic trade deficit with RUK, the environmental trade balance relationship for the main greenhouse gas, CO2, runs in the opposite direction. In other words, the findings of this study suggest the existence of a CO2 trade surplus between Scotland and the rest of the UK. This suggests that Scotland is bearing a net loss in terms of pollutants as a result of inter-union trade. However, if Scotland can carry out key activities, such as electricity generation, using less polluting technology, it is better for the UK as a whole if this type of relationship exists. Thus, the environmental trade balance is an important part of the devolution settlement
The complex stellar populations in the lines of sight to open clusters in the third Galactic quadrant
Multi-color photometry of the stellar populations in five fields in the third
Galactic quadrant centred on the clusters NGC 2215, NGC 2354, Haffner 22,
Ruprecht 11, and ESO489SC01 is interpreted in terms of a warped and flared
Galactic disk, without resort to an external entity such as the popular
Monoceros or Canis Major overdensities. Except for NGC 2215, the clusters are
poorly or unstudied previously. The data generate basic parameters for each
cluster, including the distribution of stars along the line of sight. We use
star counts and photometric analysis, without recourse to Galactic-model-based
predictions or interpretations, and confirms earlier results for NGC 2215 and
NGC 2354. ESO489SC01 is not a real cluster, while Haffner~22 is an overlooked
cluster aged about 2.5 Gyr. Conclusions for Ruprecht~11 are preliminary,
evidence for a cluster being marginal. Fields surrounding the clusters show
signatures of young and intermediate-age stellar populations. The young
population background to NGC~2354 and Ruprecht~11 lies 8-9 kpc from the Sun and
1 kpc below the formal Galactic plane, tracing a portion of the
Norma-Cygnus arm, challenging Galactic models that adopt a sharp cut-off of the
disk 12-14 kpc from the Galactic center. The old population is metal poor with
an age of 2-3 Gyr, resembling star clusters like Tombaugh 2 or NGC 2158. It has
a large color spread and is difficult to locate precisely. Young and old
populations follow a pattern that depends critically on the vertical location
of the thin and/or thick disk, and whether or not a particular line of sight
intersects one, both, or none.Comment: 16 pages, 9 eps figures, in press in MNRA
TRACKING PERFORMANCE OF A SWEPT-WING FIGHTER WITH A DIRECTORTYPE RADAR FIRE-CONTROL SYSTEM AND SCOPE PRESENTATION
Tracking performance of f-86d aircraft with radar fire-control syste
Development of computer software to analyze entire LANDSAT scenes and to summarize classification results of variable-size polygons
The Forest Pest Management Division (FPMD) of the Pennsylvania Bureau of Forestry has the responsibility for conducting annual surveys of the State's forest lands to accurately detect, map, and appraise forest insect infestations. A standardized, timely, and cost-effective method of accurately surveying forests and their condition should enhance the probability of suppressing infestations. The repetitive and synoptic coverage provided by LANDSAT (formerly ERTS) makes such satellite-derived data potentially attractive as a survey medium for monitoring forest insect damage over large areas. Forest Pest Management Division personnel have expressed keen interest in LANDSAT data and have informally cooperated with NASA/Goddard Space Flight Center (GSFC) since 1976 in the development of techniques to facilitate their use. The results of this work indicate that it may be feasible to use LANDSAT digital data to conduct annual surveys of insect defoliation of hardwood forests
Detection of Symmetry Protected Topological Phases in 1D
A topological phase is a phase of matter which cannot be characterized by a
local order parameter. It has been shown that gapped phases in 1D systems can
be completely characterized using tools related to projective representations
of the symmetry groups. We show how to determine the matrices of these
representations in a simple way in order to distinguish between different
phases directly. From these matrices we also point out how to derive several
different types of non-local order parameters for time reversal, inversion
symmetry and symmetry, as well as some more general cases
(some of which have been obtained before by other methods). Using these
concepts, the ordinary string order for the Haldane phase can be related to a
selection rule that changes at the critical point. We furthermore point out an
example of a more complicated internal symmetry for which the ordinary string
order cannot be applied.Comment: 12 pages, 9 Figure
The Pulsation Mode and Distance of the Cepheid FF Aquilae
The determination of pulsation mode and distance for field Cepheids is a
complicated problem best resolved by a luminosity estimate. For illustration a
technique based on spectroscopic luminosity discrimination is applied to the
4.47d s-Cepheid FF Aql. Line ratios in high dispersion spectra of the variable
yield values of =-3.40+-0.02 s.e.(+-0.04 s.d.), average effective
temperature Teff=6195+-24 K, and intrinsic color (-)o = +0.506+-0.007,
corresponding to a reddening of E(B-V)=0.25+-0.01, or E(B-V)(B0)=0.26+-0.01.
The skewed light curve, intrinsic color, and luminosity of FF Aql are
consistent with fundamental mode pulsation for a small amplitude classical
Cepheid on the blue side of the instability strip, not a sinusoidal pulsator. A
distance of 413+-14 pc is estimated from the Cepheid's angular diameter in
conjunction with a mean radius of =39.0+-0.7 Rsun inferred from its
luminosity and effective temperature. The dust extinction towards FF Aql is
described by a ratio of total-to-selective extinction of
Rv=Av/E(B-V)=3.16+-0.34 according to the star's apparent distance modulus.Comment: To appear in ApJ
- …