21,551 research outputs found
The ORSER System for the Analysis of Remotely Sensed Digital Data
The main effort of the University of Pennsylvania's Office for Remote Sensing of Earth Resources (ORSER) is the processing, analysis, and interpretation of multispectral data, most often supplied by NASA in the form of imagery and digital data. The facilities used for data reduction and image enhancement are described as well as the development of algorithms for producing a computer map showing various environmental and land use characteristics of data points in the analyzed scenes. The application of an (ORSER) capability for statewide monitoring of gypsy moth defoliation is discussed
Liquid-Drop Model and Quantum Resistance Against Noncompact Nuclear Geometries
The importance of quantum effects for exotic nuclear shapes is demonstrated.
Based on the example of a sheet of nuclear matter of infinite lateral
dimensions but finite thickness, it is shown that the quantization of states in
momentum space, resulting from the confinement of the nucleonic motion in the
conjugate geometrical space, generates a strong resistance against such a
confinement and generates restoring forces driving the system towards compact
geometries. In the liquid-drop model, these quantum effects are implicitly
included in the surface energy term, via a choice of interaction parameters, an
approximation that has been found valid for compact shapes, but has not yet
been scrutinized for exotic shapes.Comment: 9 pages with 3 figure
Space station automation of common module power management and distribution, volume 2
The new Space Station Module Power Management and Distribution System (SSM/PMAD) testbed automation system is described. The subjects discussed include testbed 120 volt dc star bus configuration and operation, SSM/PMAD automation system architecture, fault recovery and management expert system (FRAMES) rules english representation, the SSM/PMAD user interface, and the SSM/PMAD future direction. Several appendices are presented and include the following: SSM/PMAD interface user manual version 1.0, SSM/PMAD lowest level processor (LLP) reference, SSM/PMAD technical reference version 1.0, SSM/PMAD LLP visual control logic representation's (VCLR's), SSM/PMAD LLP/FRAMES interface control document (ICD) , and SSM/PMAD LLP switchgear interface controller (SIC) ICD
Archive data base and handling system for the Orbiter flying qualities experiment program
The OFQ archives data base and handling system assembled as part of the Orbiter Flying Qualities (OFQ) research of the Orbiter Experiments Program (EOX) are described. The purpose of the OFQ archives is to preserve and document shuttle flight data relevant to vehicle dynamics, flight control, and flying qualities in a form that permits maximum use for qualified users. In their complete form, the OFQ archives contain descriptive text (general information about the flight, signal descriptions and units) as well as numerical time history data. Since the shuttle program is so complex, the official data base contains thousands of signals and very complex entries are required to obtain data. The OFQ archives are intended to provide flight phase oriented data subsets with relevant signals which are easily identified for flying qualities research
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
Observations of Global and Local Infall in NGC 1333
We report ``infall asymmetry'' in the HCO (1--0) and (3--2) lines toward
NGC 1333, extended over , a larger extent than has been
reported be fore, for any star-forming region. The infall asymmetry extends
over a major portion of the star-forming complex, and is not limited to a
single protostar, or to a single dense core, or to a single spectral line. It
seems likely that the infall asymmetry represents inward motions, and that
these motions are physically associated with the complex. Both blue-asymmetric
and red-asymmetric lines are seen, but in both the (3--2) and (1--0) lines of
HCO the vast majority of the asymmetric lines are blue, indicating inward
motions. The (3--2) line, tracing denser gas, has the spectra with the
strongest asymmetry and these spectra are associated with the protostars IRAS
4A and 4B, which most likely indicates a warm central source is affecting the
line profiles. The (3--2) and (1--0) lines usually have the same sense of
asymmetry in common positions, but their profiles differ significantly, and the
(1--0) line appears to trace motions on much larger spatial scales than does
the (3--2) line. Line profile models fit the spectra well, but do not strongly
constrain their parameters. The mass accretion rate of the inward motions is of
order 10 M/yr, similar to the ratio of stellar mass to cluster
age.Comment: 28 pages, 11 figures, 1 colour figur
Non-collinear magnetic structures: a possible cause for current induced switching
Current induced switching in Co/Cu/Co trilayers is described in terms of
ab-initio determined magnetic twisting energies and corresponding sheet
resistances. In viewing the twisting energy as an energy flux the
characteristic time thereof is evaluated by means of the
Landau-Lifshitz-Gilbert equation using ab-initio parameters. The obtained
switching times are in very good agreement with available experimental data. In
terms of the calculated currents, scalar quantities since a classical Ohm's law
is applied, critical currents needed to switch magnetic configurations from
parallel to antiparallel and vice versa can unambiguously be defined. It is
found that the magnetoresistance viewed as a function of the current is
essentially determined by the twisting energy as a function of the relative
angle between the orientations of the magnetization in the magnetic slabs,
which in turn can also explain in particular cases the fact that after having
switched off the current the system remains in the switched magnetic
configuration. For all ab-initio type calculations the fully relativistic
Screened Korringa-Kohn-Rostoker method and the corresponding Kubo-Greenwood
equation in the context of density functional theory are applied.Comment: 20 pages, 4 tables and 15 figures, submitted to PR
Pupillometry, a bioengineering overview
The pupillary control system is examined using a microprocessor based integrative pupillometer. The real time software functions of the microprocessor include: data collection, stimulus generation and area to diameter conversion. Results of an analysis of linear and nonlinear phenomena are presented
Are young stars always associated with cold massive disks? A CO and millimeter interferometric continuum survey
The results of a combined millimeter-spectral-line and continuum survey of cold far-infrared sources selected to favor embedded young stars in the Galaxy are presented. The spectral-line observations were performed with the 5 meter antenna of the University of Texas Millimeter-Wave Observatory. High resolution continuum observations were obtained with the Owens Valley (OVRO) Millimeter-Wave Interferometer. The goal of the survey was to gain insight into the mass, temperature, and distribution of cold dust which envelopes stars during the earliest stages of their evolution. The first phase of our survey involved 1.2 arcmin resolution observations of CO-12 and CO-13 emission lines toward each source. All but two sources had detectable CO emission. We found that 40% of the sources appear to be associated with star formation as evidenced by the presence of enhanced CO-12 line widths or broad wings. At least five of these objects are associated with bipolar molecular outflows. The second phase of our survey involves high resolution 2.7 mm continuum observations with 3 interferometer baselines ranging from 15 to 55 m in length. Preliminary results indicate that about 25% of the sources in our sample have detectable continuum emission on scales less than 30 arcsec. The high percentage of sources with enhanced CO-12 line widths or broad wings indicates that a significant fraction of our samples, 40%, are likely to be young stars. The lower detection percentage in the continuum observations, 25%, suggest that such objects are not always surrounded by large concentrations of gas and dust. The continuum detection percentage for actual dust emission could be lower than that given above since emission from ionized gas could be responsible for the observed 2.7 mm emission in some objects. To get an understanding of the type of object detected in our survey, a map of one of the survey sources, L1689N, has been made using the OVRO mm interferometer
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