1,445 research outputs found
Automatic Target Cueing of Hyperspectral Image Data
Modern imaging sensors produce vast amounts data, overwhelming human analysts. One such sensor is the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) hyperspectral sensor. The AVIRIS sensor simultaneously collects data in 224 spectral bands that range from 0.4µm to 2.5µm in approximately 10nm increments, producing 224 images, each representing a single spectral band. Autonomous systems are required that can fuse important spectral bands and then classify regions of interest if all of this data is to be exploited. This dissertation presents a comprehensive solution that consists of a new physiologically motivated fusion algorithm and a novel Bayes optimal self-architecting classifier that processes the outputs of the fusion algorithm. The fusion algorithm which uses a contrast sensitivity weighted wavelet-based multiresolution analysis is shown to outperform other fusion algorithms in both visual aesthetics and signal to noise ratios. The self-architecting classifier is a Radial Basis Function (RBF) Iterative Construction Algorithm (RICA) that is designed to autonomously determine the size of its network architecture for optimal classification performance. RICA is shown to outperform several neural network algorithms, including a fixed architecture multi-layer Perceptron (MLP), a fixed architecture RBF, and an adaptive architecture MLP. A proof is also presented demonstrating that RICA produces a network which is a minimum mean squared error approximate to Bayes optimal discriminant functions. Finally, it is shown that this combination of image fusion and self-architecting classifier provide an excellent means to detect targets in hyperspectral sensor data
THRESHOLD EFFECTS IN FOOD AND AGRIBUSINESS STOCK PRICE MARKETS
This study investigates the dynamics of agribusiness stock returns and the market return for 22 firms in a switching-regression framework. Threshold levels and regression slopes are estimated and tested. Results indicate how parameters differ for alternative regimes, at what levels dynamic adjustments take place, and the adjustment time involved.Marketing,
Evolution of the Maine Lobster Co-management Law
In fisheries management circles, there is growing realization that traditional ways of managing marine resources are not working and that new approaches to management need to be tried. One of the most promising of these new approaches is co-management, where authority for managing fish stocks is shared between the industry and government agencies. This paper discusses the implementation of the new co-management system, which was initiated in the Maine lobster industry in 1995. The law has clearly been successful; it has been framed in a way to allow lobster fishermen to be able to generate rules to constrain their own exploitative effort. At the same time, a number of problems have come to the fore, not least of which was the fact that passage of one regulatory measure caused problems for certain groups of fishermen who demanded remedial legislation. Thus, the co-management effort in Maine has moved ahead by solving a sequence of problems. But the fact that these problems are being solved places Maine in the forefront of jurisdictions experimenting with new ways to manage fisheries
Overview of Heat Addition and Efficiency Predictions for an Advanced Stirling Convertor
The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two high-efficiency Advanced Stirling Convertors (ASCs), developed by Sunpower Inc. and NASA Glenn Research Center (GRC). The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot end and cold end temperatures, and specified electrical power output for a given net heat input. Microporous bulk insulation is used in the ground support test hardware to minimize the loss of thermal energy from the electric heat source to the environment. The insulation package is characterized before operation to predict how much heat will be absorbed by the convertor and how much will be lost to the environment during operation. In an effort to validate these predictions, numerous tasks have been performed, which provided a more accurate value for net heat input into the ASCs. This test and modeling effort included: (a) making thermophysical property measurements of test setup materials to provide inputs to the numerical models, (b) acquiring additional test data that was collected during convertor tests to provide numerical models with temperature profiles of the test setup via thermocouple and infrared measurements, (c) using multidimensional numerical models (computational fluid dynamics code) to predict net heat input of an operating convertor, and (d) using validation test hardware to provide direct comparison of numerical results and validate the multidimensional numerical models used to predict convertor net heat input. This effort produced high fidelity ASC net heat input predictions, which were successfully validated using specially designed test hardware enabling measurement of heat transferred through a simulated Stirling cycle. The overall effort and results are discussed
Probing shell structure and shape changes in neutron-rich sulfur isotopes through transient-field g factor measurements on fast radioactive beams of 38S and 40S
The shell structure underlying shape changes in neutron-rich nuclei near N=28
has been investigated by a novel application of the transient field technique
to measure the first-excited state g factors in 38S and 40S produced as fast
radioactive beams. There is a fine balance between proton and neutron
contributions to the magnetic moments in both nuclei. The g factor of deformed
40S does not resemble that of a conventional collective nucleus because spin
contributions are more important than usual.Comment: 10 pages, 6 figures, accepted in PR
Shell structure underlying the evolution of quadrupole collectivity in S-38 and S-40 probed by transient-field g-factor measurements on fast radioactive beams
The shell structure underlying shape changes in neutron-rich nuclei between
N=20 and N=28 has been investigated by a novel application of the transient
field technique to measure the first-excited state g factors in S-38 and S-40
produced as fast radioactive beams. Details of the new methodology are
presented. In both S-38 and S-40 there is a fine balance between the proton and
neutron contributions to the magnetic moments. Shell model calculations which
describe the level schemes and quadrupole properties of these nuclei also give
a satisfactory explanation of the g factors. In S-38 the g factor is extremely
sensitive to the occupation of the neutron p3/2 orbit above the N=28 shell gap
as occupation of this orbit strongly affects the proton configuration. The g
factor of deformed S-40 does not resemble that of a conventional collective
nucleus because spin contributions are more important than usual.Comment: 10 pages, 36 figures, accepted for publication in Physical Review
A comparison of the galaxy populations in the Coma and distant clusters: the evolution of k+a galaxies and the role of the intracluster medium
The spectroscopic properties of galaxies in the Coma cluster are compared
with those of galaxies in rich clusters at , to investigate the
evolution of the star formation history in clusters. Luminous galaxies with
and post-starburst/post-starforming (k+a) spectra which
constitute a significant fraction of galaxies in distant cluster samples are
absent in Coma, where spectacular cases of k+a spectra are found instead at
and represent a significant proportion of the cluster dwarf galaxy
population. A simple inspection of their positions on the sky indicates that
this type of galaxy does not show a preferential location within the cluster,
but the bluest and strongest-lined group of k+a's lies in projection towards
the central 1.4 Mpc of Coma and have radial velocities significantly higher
than the cluster mean. We find a striking correlation between the positions of
these young and strong post-starburst galaxies and substructure in the hot
intracluster medium (ICM) identified from {\it XMM-Newton} data, with these
galaxies lying close to the edges of two infalling substructures. This result
strongly suggests that the interaction with the dense ICM could be responsible
for the quenching of the star formation (thus creating the k+a spectrum), and
possibly, for any previous starburst. The evolution with redshift of the
luminosity distribution of k+a galaxies can be explained by a ``downsizing
effect'', with the maximum luminosity/mass of actively star-forming galaxies
infalling onto clusters decreasing at lower redshift. We discuss the possible
physical origin of this downsizing effect and the implications of our results
for current scenarios of environmental effects on the star formation in
galaxies.Comment: 21 pages, 7 figures, to appear in ApJ, version after referee's
change
An evaluation of the epidemiology of medication discrepancies and clinical significance of medicines reconciliation in children admitted to hospital.
To determine the incidence of unintended medication discrepancies in paediatric patients at the time of hospital admission; evaluate the process of medicines reconciliation; assess the benefit of medicines reconciliation in preventing clinical harm
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