36,227 research outputs found
Fast, low-ionization emission regions of the planetary nebula M2-42
Spatially resolved observations of the planetary nebula M2-42 (PN
G008.2-04.8) obtained with the Wide Field Spectrograph on the Australian
National University 2.3 m telescope have revealed the remarkable features of
bipolar collimated jets emerging from its main structure. Velocity-resolved
channel maps derived from the [N II] 6584 emission line disentangle
different morphological components of the nebula. This information is used to
develop a three-dimensional morpho-kinematic model, which consists of an
equatorial dense torus and a pair of asymmetric bipolar outflows. The expansion
velocity of about 20 km s is measured from the spectrum integrated over
the main shell. However, the deprojected velocities of the jets are found to be
in the range of 80-160 km s with respect to the nebular center. It is
found that the mean density of the collimated outflows, 595 125
cm, is five times lower than that of the main shell, 3150 cm,
whereas their singly ionized nitrogen and sulfur abundances are about three
times higher than those determined from the dense shell. The results indicate
that the features of the collimated jets are typical of fast, low-ionization
emission regions.Comment: 6 pages, 4 figures, 4 tables, accepted for publication in The
Astronomical Journa
Effective health communication in the mining industry
Historically, occupational health and safety has primarily presented as attempts to create a safer work environment for employees. The mining industry carries health and safety risks, often greater than other occupations. Whilst the mining industry is regulated by stringent workplace health and safety regulations, the very nature of the work and environmental influences expose employees to a greater number of injury risk factors than many other industries. The application of risk management techniques has resulted in a substantial decline in injury rates observed for mining operations in developed countries (Donoghue, 2004). This essential focus can be complemented by a more comprehensive approach to occupational health and safety that also supports the design and delivery of proactive health promotion programs..
Monitoring of solar far ultraviolet radiation from the OSO-5 satellite
A spectrophotometer for monitoring the solar EUV in three broad wavelength bands is described. The kind of data obtained, along with sources of error, are presented. The content of the tape library which contains the data is outlined. The scientific results are discussed. These include the following: solar flares in the EUV, solar eclipse observations in the EUV, SFD's and relationship to solar flares, and the application of satellite sunrise and sunset data for the study of model upper atmospheres for the earth
Honeycomb-laminate composite structure
A honeycomb-laminate composite structure was comprised of: (1) a cellular core of a polyquinoxaline foam in a honeycomb structure, and (2) a layer of a noncombustible fibrous material impregnated with a polyimide resin laminated on the cellular core. A process for producing the honeycomb-laminate composite structure and articles containing the honeycomb-laminate composite structure is described
Polyimide fiber-glass composite resists high temperatures
Composites synthesized from bismaleimide have superior strength and oxidation resistance at elevated temperatures when compared with similar composites prepared with epoxy or silicon polymers of similar cost. Polyimide synthesis technique and processing method yield essentially void-free fiber-glass reinforced composites
Advanced supersonic technology fuel tank sealants
Status of the fuel tank simulation and YF-12A flight tests utilizing a fluorosilicone sealant is described. New elastomer sealant development is detailed, and comparisons of high and low temperature characteristics are made to baseline fluorosilicone sealants
Effect of interfacial oxide layers on the current-voltage characteristics of Al-Si contacts
Aluminum-silicon contacts with very thin interfacial oxide layers and various surface impurity concentrations are studied for both n and p-type silicon. To determine the surface impurity concentrations on p(+)-p and n(+)-n structures, a modified C-V technique was utilized. Effects of interfacial oxide layers and surface impurity concentrations on current-voltage characteristics are discussed based on the energy band diagrams from the conductance-voltage plots. The interfacial oxide and aluminum layer causes image contrasts on X-ray topographs
Solar flare ionization in the mesosphere observed by coherent-scatter radar
The coherent-scatter technique, as used with the Urbana radar, is able to measure relative changes in electron density at one altitude during the progress of a solar flare when that altitude contains a statistically steady turbulent layer. This work describes the analysis of Urbana coherent-scatter data from the times of 13 solar flares in the period from 1978 to 1983. Previous methods of measuring electron density changes in the D-region are summarized. Models of X-ray spectra, photoionization rates, and ion-recombination reaction schemes are reviewed. The coherent-scatter technique is briefly described, and a model is developed which relates changes in scattered power to changes in electron density. An analysis technique is developed using X-ray flux data from geostationary satellites and coherent scatter data from the Urbana radar which empirically distinguishes between proposed D-region ion-chemical schemes, and estimates the nonflare ion-pair production rate
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