482 research outputs found
Parametric studies with an atmospheric diffusion model that assesses toxic fuel hazards due to the ground clouds generated by rocket launches
Parametric studies were made with a multilayer atmospheric diffusion model to place quantitative limits on the uncertainty of predicting ground-level toxic rocket-fuel concentrations. Exhaust distributions in the ground cloud, cloud stabilized geometry, atmospheric coefficients, the effects of exhaust plume afterburning of carbon monoxide CO, assumed surface mixing-layer division in the model, and model sensitivity to different meteorological regimes were studied. Large-scale differences in ground-level predictions are quantitatively described. Cloud alongwind growth for several meteorological conditions is shown to be in error because of incorrect application of previous diffusion theory. In addition, rocket-plume calculations indicate that almost all of the rocket-motor carbon monoxide is afterburned to carbon dioxide CO2, thus reducing toxic hazards due to CO. The afterburning is also shown to have a significant effect on cloud stabilization height and on ground-level concentrations of exhaust products
Combustion detector
A device has been developed for generating a rapid response signal upon the radiation-emitting combustion reaction of certain gases in order to provide a means for the detection and identification of such reaction and concurrently discriminate against spurious signals. This combustion might be the first stage of a coal mine explosion process, and thereby this device could provide a warning of the impending explosion in time to initiate quenching action. This device has the capability of distinguishing between the light emitted from a combustion reaction and the light emitted by miners' lamps, electric lamps, welding sparks or other spurious events so that the quenching mechanism is triggered only when an explosion-initiating combustion occurs
Stratospheric dynamics and transport studies
A three dimensional General Circulation Model/Transport Model is used to simulate stratospheric circulation and constituent distributions. Model simulations are analyzed to interpret radiative, chemical, and dynamical processes and their mutual interactions. Concurrent complementary studies are conducted using both global satellite data and other appropriate data. Comparisons of model simulations and data analysis studies are used to aid in understanding stratospheric dynamics and transport processes and to assess the validity of current theory and models
Polar ozone
The observation and interpretation of a large, unexpected ozone depletion over Antarctica has changed the international scientific view of stratospheric chemistry. The observations which show the veracity, seasonal nature, and vertical structure of the Antarctic ozone hole are presented. Evidence for Arctic and midlatitude ozone loss is also discussed. The chemical theory for Antarctic ozone depletion centers around the occurrence of polar stratospheric clouds (PSCs) in Antarctic winter and spring; the climatology and radiative properties of these clouds are presented. Lab studies of the physical properties of PSCs and the chemical processes that subsequently influence ozone depletion are discussed. Observations and interpretation of the chemical composition of the Antarctic stratosphere are described. It is shown that the observed, greatly enhanced abundances of chlorine monoxide in the lower stratosphere are sufficient to explain much if not all of the ozone decrease. The dynamic meteorology of both polar regions is given, interannual and interhemispheric variations in dynamical processes are outlined, and their likely roles in ozone loss are discussed
Exclusive W + photon production in proton-antiproton collisions I: general formalism
We present a detailed computation of the fully exclusive cross section of p +
antip --> W + photon + X with X = 0 and 1 jet in the framework of the
factorization theorem and dimensional regularization. Order alpha-strong and
photon bremsstrahlung contributions are discussed in the MS-bar mass
factorization scheme. The resulting expressions are ready to be implemented
numerically using Monte Carlo techniques to compute single and double
differential cross sections and correlations between outgoing pairs of
particles.Comment: ITP-SB-93-72, 40 pages, LateX. 3*4 figures in separate file.
([email protected]) ([email protected]
Incorporating next-to-leading order matrix elements for hadronic diboson production in showering event generators
A method for incorporating information from next-to-leading order QCD matrix
elements for hadronic diboson production into showering event generators is
presented. In the hard central region (high jet transverse momentum) where
perturbative QCD is reliable, events are sampled according to the first order
tree level matrix element. In the soft and collinear regions next-to-leading
order corrections are approximated by calculating the differential cross
section across the phase space accessible to the parton shower using the first
order (virtual graphs included) matrix element. The parton shower then provides
an all-orders exclusive description of parton emissions. Events generated in
this way provide a physical result across the entire jet transverse momentum
spectrum, have next-to-leading order normalization everywhere, and have
positive definite event weights. The method is generalizable without
modification to any color singlet production process.Comment: 13 pages, 9 figure
Detection of spectrally complex signals in comodulated maskers: Effect of temporal fringe
This study tested the hypothesis that masking release for a complex signal under conditions where signal energy is present in all frequency regions occupied by the masker is attributable to an across-frequency-channel comodulation masking release (CMR) process. The approach was to identify a signature CMR trait, and to then determine if that trait was associated with the detection advantage for complex signals. The selected trait was the decline of CMR in the presence of a random temporal fringe. In experiment 1, a masking release was observed for a 4-component harmonic signal presented in a comodulated masker, and this masking release was diminished by the random temporal fringe. A similar effect was observed in experiment 2 for a 4-component inharmonic signal. These results support the hypothesis that a CMR can be measured for a complex signal even when there is substantial spectral overlap between the signal and its comodulated masker. This finding has consequences for CMR models since it demonstrates that the presence of ‘signal-free’ cue bands is not a prerequisite for CMR, and that the presence of comodulation during the signal window is not sufficient to result in CMR
Does Being Bored Make Us More Creative?
Boredom has traditionally been associated with a range of negative outcomes, both within the workplace and outside it. More recently, however, it has been suggested that boredom can have positive outcomes, one of which might be increased creativity. This study addressed this proposition by examining the relationship between boredom and creative potential on a range of tasks. Two studies were carried out; the first involved 80 participants taking part in either a boring writing activity or not (control group) followed by a creative task. The second study involved a further 90 participants who varied in the type of boring activity they undertook (either a boring written activity, a boring reading activity or control) and the type of creative task that followed. Results suggested that boring activities resulted in increased creativity and that boring reading activities lead to more creativity in some circumstances (such as convergent tasks) than boring written activities. The role of daydreaming as a mediator between boredom and creativity is discussed and implications are outline
The interactive on-site inspection system: An information management system to support arms control inspections
The increasing use of on-site inspection (OSI) to meet the nation`s obligations with recently signed treaties requires the nation to manage a variety of inspection requirements. This document describes a prototype automated system to assist in the preparation and management of these inspections
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